Dynamics of semiconductor lasers

M. Radziunas, Chapter 31: Traveling Wave Modeling of Nonlinear Dynamics in Multisection Semiconductor Laser Diodes, in: Vol. 2 of Handbook of Optoelectronic Device Modeling and Simulation: Lasers, Modulators, Photodetectors, Solar Cells, and Numerical Methods, J. Piprek, ed., Series in Optics and Optoelectronics, CRC Press, Taylor & Francis Group, Boca Raton, 2017, pp. 153--182, (Chapter Published).
Abstract
A hierarchy of 1 (time) + 1 (space) dimensional first-order partial differential equation (traveling wave) models is used for a description of dynamics in individual semiconductor lasers, various multisection semiconductor lasers, and coupled laser systems. Consequent modifications of the basic traveling wave model allow for taking into account different physical effects such as the gain dispersion, the thermal detuning, the spatial hole burning of carriers, the nonlinear gain saturation, or various carrier exchange processes in quantum dot lasers. For illustration, the model was applied for simulations of dynamics in complex ring laser with four branches of filtered feedback. Finally, several advanced techniques for model analysis such as calculation of instantaneous optical modes, finding of steady states, and numerical continuation and bifurcation analysis of the model equations were discussed and illustrated by example simulations.

I. Laukaityte, R. Čiegis, M. Lichtner, M. Radziunas, Parallel Numerical Algorithm for the Traveling Wave Model, in: Parallel Scientific Computing and Optimization: Advances and Applications, R. Čiegis, D. Henty, B. Kågström, J. Žilinskas, eds., 27 of Springer Optimization and Its Applications, Springer, New York, 2008, pp. 237-251, (Chapter Published).

M. Radziunas, H.-J. Wünsche, Chapter 5: Multisection Lasers: Longitudinal Modes and Their Dynamics, in: Optoelectronic Devices --- Advanced Simulation and Analysis, J. Piprek, ed., Springer, New York, 2005, pp. 121--150, (Chapter Published).

U. Bandelow, H. Gajewski, R. Hünlich, Chapter 3: Fabry--Perot Lasers: Thermodynamics-based Modeling, in: Optoelectronic Devices --- Advanced Simulation and Analysis, J. Piprek, ed., Springer, New York, 2005, pp. 63-85, (Chapter Published).

H.-J. Wünsche, J. Piprek, U. Bandelow, H. Wenzel, eds., Proceedings of the 5th International Conference on ``Numerical Simulation of Optoelectronic Devices'' (NUSOD '05) in Berlin, September 19--22, 2005, IEEE, Piscataway, NJ, 2005, 134 pages, (Collection Published).

E. Kuhn, Simulation of the mode dynamics in broad-ridge laser diodes, IEEE Photonics Journal, 16 (2024), pp. 0601008/1--0601008/8, DOI 10.1109/JPHOT.2024.3374448 .
Abstract
In this publication a method to simulate the mode dynamics in broad-ridge laser diode is presented. These devices exhibit rich lateral mode dynamics in addition to longitudinal mode dynamics observed in narrow-ridge laser diodes. The mode dynamics are strongly influenced by higher order effects, which are described by effective interaction terms and can derived from the band structure and the carrier scattering in the quantum well. The spatial dependency of pump current densities plays a crucial role in lateral mode dynamics, and thus, a Drift-Diffusion model is employed to calculate the current densities with an additional capturing term.

L. Mertenskötter, M. Kantner, Frequency noise characterization of narrow-linewidth lasers: A Bayesian approach, IEEE Photonics Journal, 16 (2024), pp. 0601407/1--0601407/7, DOI 10.1109/JPHOT.2024.3385184 .
Abstract
We describe a Bayesian estimation approach to infer on the frequency noise characteristics of narrow-linewidth semiconductor lasers from delayed self-heterodyne beat note measurements. Our technique is grounded in a statistical model of the measurement process that accounts for both the impact of the interferometer and the detector noise. The approach yields accurate results, even in scenarios where the intrinsic linewidth plateau is obscured by detector noise. The analysis is carried out using a Markov-chain Monte Carlo method in the frequency domain and exploits prior knowledge about the statistical distribution of the data. The method is validated using simulated time series data from a stochastic laser rate equation model incorporating 1/f -type non-Markovian noise.

M. Radziunas, E. Kuhn, H. Wenzel, B. King, P. Crump, Optical mode calculation in large-area photonic crystal surface-emitting lasers, IEEE Photonics Journal, 16 (2024), pp. 1--9, DOI 10.1109/JPHOT.2024.3380532 .
Abstract
We discuss algorithms and numerical challenges in constructing and resolving spectral prob- lems for photonic crystal surface-emitting lasers (PCSELs) with photonic crystal layers and large (up to several tens of mm2) emission areas. We show that finite difference schemes created using coarse numerical meshes provide sufficient accuracy for several major (lowest-threshold) modes of particular device designs. Our technique is applied to the example of large-area all- semiconductor PCSELs, showing how it can be used to optimize device performance.

M. Radziunas, E. Kuhn, H. Wenzel, Solving a spectral problem for large-area photonic crystal surface-emitting lasers, Mathematical Modelling and Analysis. Matematinis Modeliavimis ir Analize. The Baltic Journal on Mathematical Applications, Numerical Analysis and Differential Equations, 29 (2024), pp. 575--599, DOI 10.3846/mma.2024.20496 .
Abstract
We present algorithms for constructing and resolving spectral problems for novel photonic crystal surface-emitting lasers with large emission areas, given by first-order PDEs with two spatial dimensions. These algorithms include methods to overcome computer-arithmetic-related challenges when dealing with huge and small numbers. We show that the finite difference schemes, constructed using relatively coarse numerical meshes enable accurate estimation of several major, optical modes, which are essential in practical applications.

M. Radziunas, V. Raab, Modeling and simulation of the cascaded polarization-coupled system of broad-area semiconductor lasers, IEEE Journal of Selected Topics in Quantum Electronics, 31 (2024), pp. 1501108/1--1501108/8, DOI 10.1109/JSTQE.2024.3442429 .
Abstract
We consider a brightness- and power-scalable rectified polarization beam combining scheme for high-power, broad-area edge-emitting semiconductor laser diodes. The coupling of 2m emitters is achieved through Lyot-filtered optical reinjection from a specially designed multi-stage external cavity, which forces individual diodes to lase on interleaved frequency combs with overlapping envelopes. Simulations of up to sixteen coupled emitters and analysis of the calculated beams suggest that, under ideal conditions, a beam coupling efficiency of approximately 90% can be expected. Reducing optical losses within the external cavity is crucial for improving this efficiency in experimental systems.

E. Kuhn, A. Tränhardt, Influence of scattering effects on the interaction between longitudinal modes in laser diodes, Phys. Rev. B., 108 (2023), pp. 115304/1--115304/15, DOI 10.1103/PhysRevB.108.115304 .
Abstract
A predictive model of scattering processes in semiconductor lasers is derived, enabling us to model relaxation processes starting from well-known parameters such as the dielectric constant. The resulting effective mode interaction terms are explicitly calculated for an (InGa)N quantum well using Coulomb scattering. In contrast to the method used so far to model mode competi- tion phenomena in Fabry--Pérot type laser diodes, the model correctly includes e.g. accelerated scattering at higher densities or temperatures and eliminates the scattering rate as an unknown parameter. The effective mode interaction term derived in this work can be used for the simulation of the mode dynamics in various laser diode types, for example broad area laser diodes, where multiple transversal and longitudinal modes are active. Thus, our model offers an increased pre- dictability and improved modelling of switch-on behavior.

A. Roche, S. Slepneva, A. Kovalev, A. Pimenov, A.G. Vladimirov, M. Giudici, M. Marconi, G. Huyet, Decoherence and turbulence sources in a long laser, Physical Review Letters, 131 (2023), pp. 053801/1--053801/7, DOI 10.1103/PhysRevLett.131.053801 .
Abstract
We investigate the turn-on process in a laser cavity where the roundtrip time is several orders of magnitude greater than the active medium timescales. In this long delay limit the electromagnetic field build-up can be mapped experimentally roundtrip after roundtrip. We show how coherence settles down starting from a stochastic initial condition. In the early stages of the turn-on, we show that power drop-outs emerge, persist for several round-trips and seed dark solitons. These latter structures exhibit a chaotic dynamics and emit radiation that can lead to an overall turbulent dynamics depending on the cavity dispersion.

T. Witke, E. Kuhn, F. Teichert, Ch. Gossler, U.Th. Schwarz, A. Thränhardt, Angle-dependent light scattering in tissue phantoms for the case of thin bone layers with predominant forward scattering, Journal of Biophotonics, published online on 29.11.2023, DOI 10.1002/jbio.202300358 .

M. Kantner, L. Mertenskötter, Accurate evaluation of self-heterodyne laser linewidth measurements using Wiener filters, Optics Express, 31 (2023), pp. 15994--16009, DOI 10.1364/OE.485866 .
Abstract
Self-heterodyne beat note measurements are widely used for the experimental characterization of the frequency noise power spectral density (FN-PSD) and the spectral linewidth of lasers. The measured data, however, must be corrected for the transfer function of the experimental setup in a post-processing routine. The standard approach disregards the detector noise and thereby induces reconstruction artifacts, i.e., spurious spikes, in the reconstructed FN-PSD. We introduce an improved post-processing routine based on a parametric Wiener filter that is free from reconstruction artifacts, provided a good estimate of the signal-to-noise ratio is supplied. Building on this potentially exact reconstruction, we develop a new method for intrinsic laser linewidth estimation that is aimed at deliberate suppression of unphysical reconstruction artifacts. Our method yields excellent results even in the presence of strong detector noise, where the intrinsic linewidth plateau is not even visible using the standard method. The approach is demonstrated for simulated time series from a stochastic laser model including 1 / f-type noise.

A.G. Vladimirov, Temporal cavity soliton interaction in passively mode-locked semiconductor lasers, Optics, 4 (2023), pp. 433--446, DOI 10.3390/opt4030031 .
Abstract
Weak interaction due to gain saturation and recovery of temporal cavity solitons in a delay differential model of a long cavity semiconductor laser is studied numerically and analytically using an asymptotic approach. It is shown that apart from usual soliton repulsion leading to a harmonic mode-locking regime a soliton attraction is also possible in a laser with nonzero linewidth enhancement factor. It is shown numerically that the attraction can lead either to a soliton merging or to a pulse bound state formation.

M. Radziunas, Calculation of steady states in dynamical semiconductor laser models, Optical and Quantum Electronics, 55 (2023), pp. 121/1--121/14 (published online on 17.12.2022), DOI 10.1007/s11082-022-04385-1 .
Abstract
We discuss numerical challenges in calculating stable and unstable steady states of widely used dynamical semiconductor laser models. Knowledge of these states is valuable when analyzing laser dynamics and different properties of the lasing states. The example simulations and analysis mainly rely on 1(time)+1(space)-dimensional traveling-wave models, where the steady state defining conditions are formulated as a system of nonlinear algebraic equations. The per- formed steady state calculations reveal limitations of the Lang--Kobayashi model, explain nontrivial bias threshold relations in lasers with several electrical contacts, or predict and explain transient dynamics when simulating such lasers.

A.G. Vladimirov, Short- and long-range temporal cavity soliton interaction in delay models of mode-locked lasers, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 105 (2022), pp. 044207/1--044207/6, DOI 10.1103/PhysRevE.105.044207 .
Abstract
Interaction equations governing slow time evolution of the coordinates and phases of two interacting temporal cavity solitons in a delay differential equation model of a nonlinear mirror mode-locked laser are derived and analyzed. It is shown that non-local pulse interaction due to gain depletion and recovery can lead either to a development of harmonic mode-locking regime, or to a formation of closely packed incoherent soliton bound state with weakly oscillating intersoliton time separation. Local interaction via electric field tails can result in an anti-phase or in-phase stationary or breathing harmonic mode-locking regime.

S. Slepneva, A. Pimenov, Nonlinear dynamical properties of frequency swept fiber-based semiconductor lasers, Journal of Physics: Photonics, 3 (2021), pp. 044002/1--044002/11, DOI 10.1088/2515-7647/ac1324 .
Abstract
We investigate dynamics of semiconductor lasers with fiber-based unidirectional ring cavity that can be used as frequency swept sources. We identify key factors behind the reach dynamical behaviour of such lasers using state-of-the-art experimental and analytical methods. Experimentally, we study the laser in static, quasi-static and synchronisation regimes.We apply experimental methods such as optical heterodyne or electric field reconstruction in order to characterise these regimes or study the mechanisms of transition between them. Using a delay differential equation model, we demonstrate that the presence of chromatic dispersion can lead to destabilisation of the laser modes through modulational instability, which results in undesirable chaotic emission. We characterise the instability threshold both theoretically and experimentally, and demonstrate deterioration of the FDML regime near the threshold.

M. Nizette, A.G. Vladimirov, Generalized Haus master equation model for mode-locked class-B lasers, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 104 (2021), pp. 014215/1--014215/13, DOI 10.1103/PhysRevE.104.014215 .
Abstract
Using the multiscale technique we develop a generalized version of the class-B Haus modelocking model that accounts for both the slow gain response to the averaged value of the field intensity and the fast gain dynamics on the scale comparable to the pulse duration. We show that unlike the standard class-B Haus mode-locked model, our model is able to describe not only Q-switched instability of the fundamental mode-locked regime, but also the appearance of harmonic mode-locked regimes with the increase of the pump power.

A. Zeghuzi, J.-P. Koester, M. Radziunas, H. Christopher, H. Wenzel, A. Knigge, Spatially modulated broad-area lasers for narrow lateral far-field divergence, Optics Express, 29 (2021), pp. 25133--25141, DOI 10.1364/OE.430804 .
Abstract
A novel laser design is presented that combines a longitudinal-lateral gain-loss modulation with an additional phase tailoring achieved by etching rectangular trenches. At 100 A pulsed operation, simulations predict a far-field profile with 0.3-degree full width at half maximum where a 0.4-degree-wide main lobe contains 40% of the emitted optical output power. While far-field measurements of these structured lasers emitting 10 ns long pulses with 35 W peak power confirm a substantial enhancement of radiation within the central one-degree angular range, the measured far-field intensity outside of the obtained central peak remains high.

H. Wenzel, M. Kantner, M. Radziunas, U. Bandelow, Semiconductor laser linewidth theory revisited, APPS. Applied Sciences, 11 (2021), pp. 6004/1--6004/29, DOI 10.3390/app11136004 .
Abstract
More and more applications require semiconductor lasers distinguished not only by large modulation bandwidths or high output powers, but also by small spectral linewidths. The theoretical understanding of the root causes limiting the linewidth is therefore of great practical relevance. In this paper, we derive a general expression for the calculation of the spectral linewidth step by step in a self-contained manner. We build on the linewidth theory developed in the 1980s and 1990s but look from a modern perspective, in the sense that we choose as our starting points the time-dependent coupled-wave equations for the forward and backward propagating fields and an expansion of the fields in terms of the stationary longitudinal modes of the open cavity. As a result, we obtain rather general expressions for the longitudinal excess factor of spontaneous emission (K-factor) and the effective Alpha-factor including the effects of nonlinear gain (gain compression) and refractive index (Kerr effect), gain dispersion and longitudinal spatial hole burning in multi-section cavity structures. The effect of linewidth narrowing due to feedback from an external cavity often described by the so-called chirp reduction factor is also automatically included. We propose a new analytical formula for the dependence of the spontaneous emission on the carrier density avoiding the use of the population inversion factor. The presented theoretical framework is applied to a numerical study of a two-section distributed Bragg reflector laser.

A.G. Vladimirov, S. Suchkov, G. Huyet, S.K. Turitsyn, Delay-differential-equation model for mode-locked lasers based on nonlinear optical and amplifying loop mirrors, Physical Review A, 104 (2021), pp. 033525/1--033525/8, DOI 10.1103/PhysRevA.104.033525 .
Abstract
Delay differential equation model of a NOLM-NALM mode-locked laser is developed that takes into account finite relaxation rate of the gain medium and asymmetric beam splitting at the entrance of the nonlinear mirror loop. Asymptotic linear stability analysis of the continuous wave solutions performed in the limit of large delay indicates that in a class-B laser flip instability leading to a period doubling cascade and development of square-wave patterns can be suppressed by a short wavelength modulational instability. Numerically it is shown that the model can demonstrate large windows of regular fundamental and harmonic mode-locked regimes with single and multiple pulses per cavity round trip time separated by domains of irregular pulsing.

A. Pimenov, S. Amiranashvili, A.G. Vladimirov, Temporal cavity solitons in a delayed model of a dispersive cavity ring laser, Mathematical Modelling of Natural Phenomena, 15 (2020), pp. 47/1--47/18, DOI 10.1051/mmnp/2019054 .
Abstract
Nonlinear localised structures appear as solitary states in systems with multistability and hysteresis. In particular, localised structures of light known as temporal cavity solitons were observed recently experimentally in driven Kerr-cavities operating in the anomalous dispersion regime when one of the two bistable spatially homogeneous steady states exhibits a modulational instability. We use a distributed delay system to study theoretically the formation of temporal cavity solitons in an optically injected ring semiconductor-based fiber laser, and propose an approach to derive reduced delay-differential equation models taking into account the dispersion of the intracavity fiber delay line. Using these equations we perform the stability and bifurcation analysis of injection-locked continuous wave states and temporal cavity solitons.

U. Gowda, A. Roche, A. Pimenov, A.G. Vladimirov, S. Slepneva, E.A. Viktorov, G. Huyet, Turbulent coherent structures in a long cavity semiconductor laser near the lasing threshold, Optics Letters, 45 (2020), pp. 4903--4906, DOI 10.1364/OL.397840 .
Abstract
We report on the formation of novel turbulent coherent structures in a long cavity semiconductor laser near the lasing threshold. Experimentally, the laser emits a series of power dropouts within a roundtrip, and the number of dropouts per series depends on a set of parameters including the bias current. At fixed parameters, the drops remain dynamically stable, repeating over many roundtrips. By reconstructing the laser electric field in the case where the laser emits one dropout per roundtrip and simulating its dynamics using a time-delayed model, we discuss the reasons for long-term sustainability of these solutions. We suggest that the observed dropouts are closely related to the coherent structures of the cubic complex Ginzburg--Landau equation.

A.V. Kovalev, P.S. Dmitriev, A.G. Vladimirov, A. Pimenov, G. Huyet, E.A. Viktorov, Bifurcation structure of a swept-source laser, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 101 (2020), pp. 012212/1--012212/5, DOI 10.1103/PhysRevE.101.012212 .
Abstract
We numerically analyze a delay differential equation model of a short-cavity semiconductor laser with an intracavity frequency-swept filter and reveal a complex bifurcation structure responsible for the asymmetry of the output characteristics of this laser. We show that depending on the direction of the frequency sweep of a narrow-band filter, there exist two bursting cycles determined by different parts of a continuous-wave solutions branch.

J.-P. Köster, A. Putz, H. Wenzel, H.-J. Wünsche, M. Radziunas, H. Stephan, M. Wilkens, A. Zeghuzi, A. Knigge, Mode competition in broad-ridge-waveguide lasers, Semiconductor Science and Technology, 36 (2020), pp. 015014/1--015014/12, DOI 10.1088/1361-6641/abc6e7 .
Abstract
The lateral brightness achievable with high-power GaAs-based laser diodes having long and broad waveguides is commonly regarded to be limited by the onset of higher-order lateral modes. For the study of the lateral-mode competition two complementary simulation tools are applied, representing different classes of approximations. The first tool bases on a completely incoherent superposition of mode intensities and disregards longitudinal effects like spatial hole burning, whereas the second tool relies on a simplified carrier transport and current flow. Both tools yield agreeing power-current characteristics that fit the data measured for 5 to 23 µm wide ridges. Also, a similarly good qualitative conformance of the near and far fields is found. However, the threshold of individual modes, the partition of power between them at a given current, and details of the near and far fields show differences. These differences are the consequence of a high sensitivity of the mode competition to details of the models and of the device structure. Nevertheless, it can be concluded concordantly that the brightness rises with increasing ridge width irrespective of the onset of more and more lateral modes. The lateral brightness 2W · mm¯¹ 1mrad¯¹ at 10MW · cm¯²2 power density on the front facet of the investigated laser with widest ridge (23 µm) is comparable with best values known from much wider broad-area lasers. In addition, we show that one of the simulation tools is able to predict beam steering and coherent beam

A.G. Vladimirov, K. Panajotov, M. Tlidi, Orthogonally polarized frequency combs in a mode-locked VECSEL, Optics Letters, 45 (2020), pp. 252--255, DOI 10.1364/OL.45.000252 .
Abstract
We introduce a spin?flip model for a vertical-external-cavity surface-emitting laser (VECSEL) with a saturable absorber. We demonstrate the possibility, due to the spin?flip dynamics, to generate two orthogonally linearly polarized frequency combs in the mode-locked regime. The two combs are shifted in wavelength due to the birefringence in the VECSEL gain and/or saturable absorption mirror. We show that the polarization degree of freedom may also lead to several pulses being generated per roundtrip in the two orthogonal linear polarizations and to more complicated dynamics with both linear polarizations excited.

C. Brée, V. Raab, J. Montiel-Ponsoda, G. Garre-Werner, K. Staliunas, U. Bandelow, M. Radziunas, Beam-combining scheme of high-power broad-area semiconductor lasers with Lyot-filtered reinjection: Modeling, simulations, and experiments, Journal of the Optical Society of America. B, 36 (2019), pp. 1721--1730, DOI 10.1364/JOSAB.36.001721 .
Abstract
A brightness- and power-scalable polarization beam combining scheme for high-power, broadarea semiconductor laser diodes is investigated numerically and experimentally. To achieve the beam combining, we employ Lyot-filtered optical reinjection from an external cavity, which forces lasing of the individual diodes on interleaved frequency combs with overlapping envelopes and enables a high optical coupling efficiency. Unlike conventional spectral beam combining schemes with diffraction gratings, the optical coupling efficiency is insensitive to thermal drifts of laser wavelengths. This scheme can be used for efficient coupling of a large number of laser diodes and paves the way towards using broad-area laser diode arrays for cost-efficient material processing, which requires high-brilliance emission and optical powers in the kW-regime.

A. Pimenov, A.G. Vladimirov, Dynamics of an inhomogeneously broadened passively mode-locked laser, The European Physical Journal B. Condensed Matter and Complex Systems, 92 (2019), pp. 114/1--114/12, DOI 10.1140/epjb/e2019-90642-8 .
Abstract
We study theoretically the effect of inhomogeneous broadening of the gain and absorption lines on the dynamics of a passively mode-locked laser. We demonstrate numerically using travelling wave equations the formation of a Lamb-dip instability and suppression of Q-switching in a laser with large inhomogeneous broadening. We derive simplified delay-differential equation model for a mode-locked laser with inhomogeneously broadened gain and absorption lines and perform numerical bifurcation analysis of this model.

A. Stephan, H. Stephan, Memory equations as reduced Markov processes, Discrete and Continuous Dynamical Systems, 39 (2019), pp. 2133--2155, DOI 10.3934/dcds.2019089 .
Abstract
A large class of linear memory differential equations in one dimension, where the evolution depends on the whole history, can be equivalently described as a projection of a Markov process living in a higher dimensional space. Starting with such a memory equation, we give an explicit construction of the corresponding Markov process. From a physical point of view the Markov process can be understood as the change of the type of some quasiparticles along one-way loops. Typically, the arising Markov process does not have the detailed balance property. The method leads to a more realisitc modeling of memory equations. Moreover, it carries over the large number of investigation tools for Markov processes to memory equations, like the calculation of the equilibrium state, the asymptotic behavior and so on. The method can be used for an approximative solution of some degenerate memory equations like delay differential equations.

M. Krüger, V.Z. Tronciu, A. Bawamia, Ch. Kürbis, M. Radziunas, H. Wenzel, A. Wicht, A. Peters, G. Tränkle, Improving the spectral performance of extended cavity diode lasers using angled-facet laser diode chips, Applied Physics B: Lasers and Optics, 66 (2019), pp. 125/1--125/12, DOI 10.1007/s00340-019-7178-z .
Abstract
We present and compare theoretical and experimental results on the electro-optical performance of extended cavity diode lasers (ECDLs) that employ two ridge waveguide designs for the single-transverse mode GaAs laser diode chip. One facet of the laser diode chips serves as a partially reflective output coupler for the laser cavity. The other facet constitutes an intra-cavity interface which introduces spurious optical feedback to the laser diode chip. The waveguide designs differ with respect to the suppression of this spurious feedback. The first design employs a straight ridge waveguide intersecting both facets at normal incidence. The intra-cavity facet is anti-reflection coated and features a residual intensity reflectivity of the order 10?4. The second design employs a bent ridge waveguide intersecting the anti-reflection-coated intra-cavity facet at an appropriate angle. This provides an additional suppression of the spurious intensity reflection to a value estimated to be less than 10?6 . We compare the electro-optical performance of both designs theoretically and experimentally. The utilization of a bent waveguide results in an improved spectral stability and purity, specifically a higher side mode suppression and a small intrinsic spectral linewidth over the whole investigated current range, of the external cavity diode laser without sacrificing other parameters such as the output power. The external cavity diode lasers under study exhibit no degradation of the measured frequency noise power spectra and intrinsic linewidths even if there is a drop of the side mode suppression ratio provided that it is not reduced to a very small value. Thus, the usage of a more readily accessible straight waveguide chip in an ECDL could be sufficient if only a limited tuning range and a particularly compact assembly are needed. For spectroscopic applications requiring a small intrinsic spectral linewidth over a large frequency range a bent waveguide chip could be the better choice.

A. Zeghuzi, M. Radziunas, H.-J. Wünsche, J.-P. Koester, H. Wenzel, U. Bandelow, A. Knigge, Traveling wave analysis of non-thermal far-field blooming in high-power broad-area lasers, IEEE J. Quantum Electron., 55 (2019), pp. 2000207/1--2000201/7, DOI 10.1109/JQE.2019.2893352 .
Abstract
With rising current the lateral far-field angle of high-power broad-area lasers widens (far-field blooming) which can be partly attributed to non-thermal effects due to carrier induced refractive index and gain changes that become the dominant mechanism under pulsed operation. To analyze the nonthermal contribution to far-field blooming we use a traveling wave based model that properly describes the injection of the current into and the diffusion of the carriers within the active region. Although no pre-assumptions regarding the modal composition of the field is made and filamentation is automatically accounted for, the highly dynamic time-dependent optical field distribution can be very well represented by only few modes of the corresponding stationary waveguide equation obtained by a temporal average of the carrier density and field intensity. The reduction of current spreading and spatial holeburning by selecting proper design parameters can substantially improve the beam quality of the laser.

J.-P. Koester, M. Radziunas, A. Zeghuzi, H. Wenzel, A. Knigge, Simulation and design of a compact GaAs based tunable dual-wavelength diode laser system, Optical and Quantum Electronics, 51 (2019), pp. 334/1--334/12, DOI 10.1007/s11082-019-2050-2 .
Abstract
We present our design of a compact, integrated and tunable dual-wavelength diode laser system emitting around 785 nm, which is of interest for several applications like Raman spectroscopy and the generation of THz radiation. To achieve a more compact device compared to previous GaAs based designs two etch depths are realized, leading to shallowly etched ridge waveguides in regions were optical gain is applied and deeply etched waveguides used to enable compact integrated waveguide components. The device parameters are optimized using a numerically efficient simulation tool for passive waveguides. Subsequently, the entire laser system is further analyzed applying a sophisticated traveling-wave equation based model for active devices giving access to internal intensity and carrier density distributions. It is shown that active laser simulations are crucial to deduce critical and performance limiting design aspects not accessible via an all-passive simulation.

A. Zeghuzi, H.-J. Wünsche, H. Wenzel, M. Radziunas, J. Fuhrmann, A. Klehr, U. Bandelow, A. Knigge, Time-dependent simulation of thermal lensing in high-power broad-area semiconductor lasers, IEEE J. Select. Topics Quantum Electron., 25 (2019), pp. 1502310/1--1502310/10, DOI 10.1109/JSTQE.2019.2925926 .
Abstract
We propose a physically realistic and yet numerically applicable thermal model to account for short and long term self-heating within broad-area lasers. Although the temperature increase is small under pulsed operation, a waveguide that is formed within a few-ns-long pulse can result in a transition from a gain-guided to an index-guided structure, leading to near and far field narrowing. Under continuous wave operation the longitudinally varying temperature profile is obtained self-consistently. The resulting unfavorable narrowing of the near field can be successfully counteracted by etching trenches.

M. Radziunas, D.J. Little, D.M. Kane, Numerical study of optical feedback coherence in semiconductor laser dynamics, Optics Letters, 44 (2019), pp. 4207--4210, DOI 10.1364/OL.44.004207 .
Abstract
The nonlinear dynamics of semiconductor laser with coherent, as compared to incoherent, delayed optical feedback systems have been discussed and contrasted in prior research literature. Here, we report simulations of how the dynamics change as the coherence of the optical feedback is systematically varied from being coherent to incoherent. An increasing rate of phase disturbance is used to vary the coherence. An edge emitting, 830nm, Fabry Perot semiconductor laser with a long external cavity is simulated. Following this study, consideration of prior and future experimental studies should include evaluation of where on the continuum of partial coherence the delayed optical feedback sits. Partial coherence is a parameter that will affect the dynamics.

M. Radziunas, J. Fuhrmann, A. Zeghuzi, H.-J. Wünsche, Th. Koprucki, C. Brée, H. Wenzel, U. Bandelow, Efficient coupling of dynamic electro-optical and heat-transport models for high-power broad-area semiconductor lasers, Optical and Quantum Electronics, 51 (2019), pp. 69/1--69/10, DOI 10.1007/s11082-019-1792-1 .
Abstract
In this work, we discuss the modeling of edge-emitting high-power broad-area semiconductor lasers. We demonstrate an efficient iterative coupling of a slow heat transport (HT) model defined on multiple vertical-lateral laser cross-sections with a fast dynamic electro-optical (EO) model determined on the longitudinal-lateral domain that is a projection of the device to the active region of the laser. Whereas the HT-solver calculates temperature and thermally-induced refractive index changes, the EO-solver exploits these distributions and provides time-averaged field intensities, quasi-Fermi potentials, and carrier densities. All these time-averaged distributions are used repetitively by the HT-solver for the generation of the heat sources entering the HT problem solved in the next iteration step.

A.G. Vladimirov, A.V. Kovalev, E.A. Viktorov, N. Rebrova, G. Huyet, Dynamics of a class-A nonlinear mirror mode-locked laser, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 100 (2019), pp. 012216/1--012216/7, DOI 10.1103/PhysRevE.100.012216 .
Abstract
Using a simple delay differential equation model we study theoretically the dynamics of a unidirectional class-A ring laser with a nonlinear amplifying loop mirror. We perform analytical linear stability analysis of the CW regimes in the large delay limit and demonstrate that these regimes can be destabilized via modulational and Turing-type instabilities, as well as by a bifurcation leading to the appearance of square-waves. We investigate the formation of square-waves and mode-locked pulses in the system. We show that mode-locked pulses are very asymmetric with exponential decay of the trailing and superexponential growth of the leading edge. We discuss asymmetric interaction of these pulses leading to a formation of harmonic mode-locked regimes.

C. Brée, D. Gailevičius, V. Purlys, G.G. Werner, K. Staliunas, A. Rathsfeld, G. Schmidt, M. Radziunas, Chirped photonic crystal for spatially filtered optical feedback to a broad-area laser, Journal of Optics, 20 (2018), pp. 095804/1--095804/7, DOI 10.1088/2040-8986/aada98 .
Abstract
We derive and analyze an efficient model for reinjection of spatially filtered optical feedback from an external resonator to a broad area, edge emitting semiconductor laser diode. Spatial filtering is achieved by a chirped photonic crystal, with variable periodicity along the optical axis and negligible resonant backscattering. The optimal chirp is obtained from a genetic algorithm, which yields solutions that are robust against perturbations. Extensive numerical simulations of the composite system with our optoelectronic solver indicate that spatially filtered reinjection enhances lower-order transversal optical modes in the laser diode and, consequently, improves the spatial beam quality.

A. Pimenov, J. Javaloyes, S.V. Gurevich, A.G. Vladimirov, Light bullets in a time-delay model of a wide-aperture mode-locked semiconductor laser, Philosophical Transactions of the Royal Society A : Mathematical, Physical & Engineering Sciences, 376 (2018), pp. 20170372/1--20170372/14, DOI 10.1098/rsta.2017.0372 .
Abstract
Recently, a mechanism of formation of light bullets (LBs) in wide-aperture passively modelocked lasers was proposed. The conditions for existence and stability of these bullets, found in the long cavity limit, were studied theoretically under the mean field (MF) approximation using a Haus-type model equation. In this paper we relax the MF approximation and study LB formation in a model of a wide-aperture three section laser with a long diffractive section and short absorber and gain sections. To this end we derive a nonlocal delay-differential equation (NDDE) model and demonstrate by means of numerical simulations that this model supports stable LBs. We observe that the predictions about the regions of existence and stability of the LBs made previously using MF laser models agree well with the results obtained using the NDDE model. Moreover, we demonstrate that the general conclusions based upon the Haus model that regard the robustness of the LBs remain true in the NDDE model valid beyond the MF approximation, when the gain, losses and diffraction per cavity round-trip are not small perturbations anymore.

M. Khoder, M. Radziunas, V. Tronciu, G. Verschaffelt, Study of wavelength switching time in tunable semiconductor micro-ring lasers: Experiment and travelling wave description, OSA Continuum, 1 (2018), pp. 1226-1240, DOI 10.1364/OSAC.1.001226 .
Abstract
We report in this paper the wavelength switching features of semiconductor ring lasers that are wavelength tunable based on filtered optical feedback. The filtered feedback provides a wavelength dependent loss mechanism in these devices with which a particular longitudinal mode, and thus a particular wavelength, can be selected by changing the filter characteristics of the feedback channel. We investigate how the wavelength switching speed depends on the amplitude of the modulation of the switching driving signal and on the different phase factors within the filtering branches of the SRL. We compare qualitatively the experimental results with numerical simulations based on a travelling wave model. We also investigate the dynamical behavior of the lasing and nonlasing longitudinal modes in the two channels of the clockwise and the counter-clockwise directions. We show the crucial importance of various phase relation factors on the wavelength switching behavior. Finally, we discuss what limits the switching speed and how we can accelerate it.

V.Z. Tronciu, H. Wenzel, M. Radziunas, M. Reggentin, J. Wiedmann, A. Knigge, Investigation of red-emitting distributed Bragg reflector lasers by means of numerical simulations, IET Optoelectronics, 12 (2018), pp. 228-232, DOI 10.1049/iet-opt.2018.0025 .
Abstract
The authors report theoretical and experimental results on the properties of distributed Bragg reflector semiconductor lasers. Using the traveling wave equation model, they show that a proper choice of coupling coefficient and front facet reflectivity allows an optimisation of the laser operation, such that for wide range of injected current into the active region the laser emits a temporally stable output power. The numerical results are in a qualitative agreement with the measured characteristics.

A. Zeghuzi, M. Radziunas, H.-J. Wünsche, A. Klehr, H. Wenzel, A. Knigge, Influence of nonlinear effects on the characteristics of pulsed high-power broad-area distributed Bragg reflector lasers, Optical and Quantum Electronics, 50 (2018), pp. 88/1--88/12, DOI 10.1007/s11082-017-1297-8 .
Abstract
We theoretically analyze the influence of nonlinear effects such as spatial holeburning, two-photon absorption and gain compression on the power?current and beam characteristics of a high-power broad-area distributed Bragg reflector laser with a stripe width of 50 ?m operated in pulsed mode and compare them with simulations of a similar Fabry?Pérot laser. On the one hand, spatial holeburning leads to a higher mean intensity within the cavity for a Fabry?Pérot laser and resulting higher losses in combination with two-photon absorption and gain compression, on the other hand, excitation of higher order lateral modes leads to losses through the Bragg grating. In combination with spatio-temporal power variations resolved by the utilized time-dependent traveling wave model two-photon absorption leads to higher power losses compared to those models using averaged powers.

M. Radziunas, M. Khoder, V. Tronciu, J. Danckaert, G. Verschaffelt, Semiconductor ring laser with filtered optical feedback: Traveling wave description and experimental validation, Journal of the Optical Society of America. B, 35, pp. 380--390, DOI 10.1364.JOSAB.35.000380 .
Abstract
We study experimentally and theoretically a semiconductor ring laser with four filtering channels providing filtered delayed optical feedback. To describe and analyze the wavelength selection and tuning in this device, we exploit the traveling-wave model determining the evolution of optical fields and carrier density along the ring cavity and filtering branches. The numerical results agree with the experimental observations: we can reproduce the wavelength tuning, the multiple wavelength emission, and the wavelength switching speed measured in these devices. The traveling-wave model allows us to study in detail the effect of the different laser parameters and can be useful for designing the future devices.

M. Radziunas, Modeling and simulations of broad-area edge-emitting semiconductor devices, Int. J. High Perform. Comput. Appl., 32 (2018), pp. 512--522, DOI 10.1177/1094342016677086 .
Abstract
We present a (2+1)-dimensional partial differential equation model for spatial-lateral dynamics of edge-emitting broad-area semiconductor devices and several extensions of this model describing different physical effects. MPI-based parallelization of the resulting middlesize numerical problem is implemented and tested on the blade cluster and separate multi-core computers at the Weierstrass Institute in Berlin. It was found, that an application of 25-30 parallel processes on all considered platforms was guaranteeing a nearly optimal performance of the algorithm with the speedup around 20-25 and the efficiency of 0.7-0.8. It was also shown, that a simultaneous usage of several in-house available multi-core computers allows a further increase of the speedup without a significant loss of the efficiency. Finally, an importance of the considered problem and the efficient numerical simulations of this problem were illustrated by a few examples occurring in real world applications.

A. Pimenov, S. Slepneva, G. Huyet, A.G. Vladimirov, Dispersive time-delay dynamical systems, Physical Review Letters, 118 (2017), pp. 193901/1--193901/6.
Abstract
We present a theoretical approach to model the dynamics of a dispersive nonlinear system using a set of delay differential equations with distributed delay term. We illustrate the use of this approach by considering a frequency swept laser comprimising a semiconductor optical amplifier (SOA), a tunable bandpass filter and a long dispersive fiber delay line. We demonstrate that this system exhibits a rich spectrum of dynamical behaviors which are in agreement with the experimental observations. In particular, the multimode modulational instability observed experimentally in the laser in the anomalous dispersion regime and leading to a turbulent laser output was found analytically in the limit of large delay time.

S. Rauch, H. Wenzel, M. Radziunas, M. Haas, G. Tränkle, H. Zimer, Impact of longitudinal refractive index change on the near-field width of high-power broad-area diode lasers, Applied Physics Letters, 110 (2017), pp. 263504/1--263504/5, DOI 10.1063/1.4990531 .
Abstract
Typical for broad-area laser (BAL) diodes operating in a continuous-wave mode is a narrowing of the near-field (NF) width at the output facet for high injection currents (output powers). This phenomenon increases the facet load of BALs, resulting in a reduction in the level of catastrophic optical mirror damage. In this letter, we demonstrate theoretically that thermally induced changes in the refractive index in both lateral and longitudinal directions not only cause the NF narrowing at the front facet but also a broadening of the NF at the back facet. In contrast, a sole lateral self-heating induced variation in the refractive index (commonly referred to as thermal lensing) does not result in a NF narrowing. Our theoretical findings are confirmed by measurements of the current-dependent profiles of the NF at the back and front facets of a BAL with a stripe width of 120??m emitting at 960?nm. Furthermore, our quasi three-dimensional thermo-electro-optic simulations indicate that a longitudinally homogeneous device temperature can reduce the front-facet load while keeping the beam quality unchanged compared with the experimental results.

T. Schemmelmann, F. Tabbert, A. Pimenov, A.G. Vladimirov, S.V. Gurevich, Delayed feedback control of self-mobile cavity solitons in a wide-aperture laser with a saturable absorber, Chaos. An Interdisciplinary Journal of Nonlinear Science, 27 (2017), pp. 114304/1--114304/9.
Abstract
We investigate the spatiotemporal dynamics of cavity solitons in a broad area vertical-cavity surface-emitting laser with saturable absorption subjected to time-delayed optical feedback. Using a combination of analytical, numerical and path continuation methods we analyze the bifurcation structure of stationary and moving cavity solitons and identify two different types of traveling localized solutions, corresponding to slow and fast motion. We show that the delay impacts both stationary and moving solutions either causing drifting and wiggling dynamics of initially stationary cavity solitons or leading to stabilization of intrinsically moving solutions. Finally, we demonstrate that the fast cavity solitons can be associated with a lateral mode-locking regime in a broad-area laser with a single longitudinal mode.

M. Radziunas, A. Zeghuzi, J. Fuhrmann, Th. Koprucki, H.-J. Wünsche, H. Wenzel, U. Bandelow, Efficient coupling of inhomogeneous current spreading and dynamic electro-optical models for broad-area edge-emitting semiconductor devices, Optical and Quantum Electronics, 49 (2017), pp. 332/1--332/8, DOI 10.1007/s11082-017-1168-3 .
Abstract
We extend a 2 (space) + 1 (time)-dimensional traveling wave model for broad-area edge-emitting semiconductor lasers by a model for inhomogeneous current spreading from the contact to the active zone of the laser. To speedup the performance of the device simulations, we suggest and discuss several approximations of the inhomogeneous current density in the active zone.

D. Peschka, M. Thomas, A. Glitzky, R. Nürnberg, M. Virgilio, S. Guha, Th. Schröder, G. Cappellini, Th. Koprucki, Robustness analysis of a device concept for edge-emitting lasers based on strained germanium, Optical and Quantum Electronics, 48 (2016), pp. 156/1--156/7, DOI 10.1007/s11082-016-0394-4 .
Abstract
We consider a device concept for edge-emitting lasers based on strained germanium microstrips. The device features an inhomogeneous tensile strain distribution generated by a SiN stressor deposited on top of the Ge microstrip. This geometry requires a lateral contact scheme and hence a full two-dimensional description. The two-dimensional simulations of the carrier transport and of the optical field, carried out in a cross section of the device orthogonal to the optical cavity, use microscopic calculations of the strained Ge material gain as an input. In this paper we study laser performance and robustness against Shockley-Read-Hall lifetime variations and device sensitivity to different strain distributions.

G. Slavcheva, A.V. Gorbach, A. Pimenov, Coupled spatial multimode solitons in microcavity wires, Phys. Rev. B., 94 (2016), pp. 245432/1--245432/13, DOI 10.1103/PhysRevB.94.245432 .
Abstract
A modal expansion approach is developed and employed to investigate and elucidate the nonlinear mechanism behind the multistability and formation of coupled multimode polariton solitons in microcavity wires. With pump switched on and realistic dissipation parameters, truncating the expansion up to the second-order wire mode, our model predicts two distinct coupled soliton branches: stable and unstable. Modulational stability of the stationary homogeneous solution and soliton branches stability are studied. Our simplified 1D model is in remarkably good agreement with the full 2D mean-field Gross-Pitaevskii model, reproducing correctly the soliton existence domain upon variation of pump amplitude and the onset of multistability.

R.M. Arkhipov, T. Habruseva, A. Pimenov, M. Radziunas, G. Huyet, A.G. Vladimirov, Semiconductor mode-locked lasers with coherent dual mode optical injection: Simulations, analysis and experiment, Journal of the Optical Society of America. B, 33 (2016), pp. 351--359.
Abstract
Using a delay differential equations model we study the dynamics of a passively mode-locked semiconductor laser with dual frequency coherent optical injection. The locking regions where the laser pulse repetition rate is synchronized to the separation of the two injected frequencies were calculated numerically and measured experimentally. Asymptotic analysis performed in the limit of the small injection field amplitude revealed the dependence of the locking regions on the model parameters, such as optical bandwith, absorber recovery time and linear losses.

D. Puzyrev, A.G. Vladimirov, S.V. Gurevich, S. Yanchuk, Modulational instability and zigzagging of dissipative solitons induced by delayed feedback, Physical Review A, 93 (2016), pp. 041801/1--041801/5.
Abstract
We report a destabilization mechanism of localized solutions in spatially extended systems which is induced by delayed feedback. Considering a model of a wide-aperture laser with a saturable absorber and delayed optical feedback, we demonstrate the appearance of multiple coexistent laser cavity solitons. We show that at large delays apart from the drift and phase instabilities the soliton can exhibit a delay-induced modulational instability associated with the translational neutral mode. The combination of drift and modulational instabilities produces a zigzagging motion of the solitons, which are either periodic, with the period close to the delay time, or chaotic, with low-frequency fluctuations in the direction of the soliton motion. The same type of modulational instability is demonstrated for localized solutions of the cubic-quintic complex Ginzburg-Landau equation.

M. Radziunas, Modeling and simulations of broad-area edge-emitting semiconductor devices, Int. J. High Perform. Comput. Appl., (2016), published online on 23.12.2016, DOI 10.1177/1094342016677086 .
Abstract
We present a (2+1)-dimensional partial differential equation model for spatial-lateral dynamics of edge-emitting broad-area semiconductor devices and several extensions of this model describing different physical effects. MPI-based parallelization of the resulting middlesize numerical problem is implemented and tested on the blade cluster and separate multi-core computers at the Weierstrass Institute in Berlin. It was found, that an application of 25-30 parallel processes on all considered platforms was guaranteeing a nearly optimal performance of the algorithm with the speedup around 20-25 and the efficiency of 0.7-0.8. It was also shown, that a simultaneous usage of several in-house available multi-core computers allows a further increase of the speedup without a significant loss of the efficiency. Finally, an importance of the considered problem and the efficient numerical simulations of this problem were illustrated by a few examples occurring in real world applications.

M. Radziunas, New multi-mode delay differential equation model for lasers with optical feedback, Optical and Quantum Electronics, 48 (2016), pp. 1--9, DOI 10.1007/s11082-016-0736-2 .
Abstract
In this paper, we discuss the relations between the spatially-distributed traveling wave, Lang-Kobayashi, and a new multi-mode delay differential equation models for Fabry-Perot type semiconductor diode lasers with an external optical feedback. All these models govern the dynamics of the slowly varying complex amplitudes of the optical fields and carrier density. To compare the models, we calculate the cavity modes determined by the threshold carrier density and optical frequency of the steady states in all three models. These calculations show that the Lang-Kobayashi type model is in good agreement with the traveling wave model only for the small feedback regimes, whereas newly derived multi-mode delay differential equation model remains correct even at moderate and large optical feedback regimes.

M. Radziunas, New multi-mode delay differential equation model for lasers with optical feedback, Optical and Quantum Electronics, 48 (2016), pp. 470/1--470/9, DOI 10.20347/WIAS.PREPRINT.2294 .
Abstract
In this paper, we discuss the relations between the spatially-distributed traveling wave, Lang-Kobayashi, and a new multi-mode delay differential equation models for Fabry-Perot type semiconductor diode lasers with an external optical feedback. All these models govern the dynamics of the slowly varying complex amplitudes of the optical fields and carrier density. To compare the models, we calculate the cavity modes determined by the threshold carrier density and optical frequency of the steady states in all three models. These calculations show that the Lang-Kobayashi type model is in good agreement with the traveling wave model only for the small feedback regimes, whereas newly derived multi-mode delay differential equation model remains correct even at moderate and large optical feedback regimes.

L. Jaurigue, A. Pimenov, D. Rachinskii, E. Schöll, K. Lüdge, A.G. Vladimirov, Timing jitter of passively-mode-locked semiconductor lasers subject to optical feedback: A semi-analytic approach, Physical Review A, 92 (2015), pp. 053807/1--053807/11.
Abstract
We propose a semi-analytical method of calculating the timing fluctuations in mode-locked semiconductor lasers and apply it to study the effect of delayed coherent optical feedback on pulse timing jitter in these lasers. The proposed method greatly reduces computation times and therefore allows for the investigation of the dependence of timing fluctuations over greater parameter domains. We show that resonant feedback leads to a reduction in the timing jitter and that a frequency-pulling region forms about the main resonances, within which a timing jitter reduction is observed. The width of these frequency-pulling regions increases linearly with short feedback delay times. We derive an analytic expression for the timing jitter, which predicts a monotonic decrease in the timing jitter for resonant feedback of increasing delay lengths, when timing jitter effects are fully separated from amplitude jitter effects. For long feedback cavities the decrease in timing jitter scales approximately as $1/tau$ with the increase of the feedback delay time $tau$.

W. Ahmed, S. Kumar, R. Herrero, M. Botey, M. Radziunas, K. Staliunas, Stabilization of flat-mirror vertical-external-cavity surface-emitting lasers by spatiotemporal modulation of the pump profile, Physical Review A, 92 (2015), pp. 043829/1--043829/8.
Abstract
We propose and demonstrate theoretically that vertical-external-cavity surface-emitting lasers (VECSELs) with external flat mirrors can be stabilized by applying a periodic spatiotemporal modulation of the pump current. Such pump modulation is shown to suppress the pattern-forming instabilities (modulation instabilities), which eventually results in stable beam emission. A modified Floquet linear stability analysis is used to characterize the dynamics of the modulated system and to evaluate its stabilization performance. Stability maps identify the regions in parameter space for complete and partial stabilization of VECSELs operating in different regimes depending on the external-cavity length. In particular, the stabilization method is shown to operate most efficiently in Class-A laser limit (for relatively long VECSEL resonators), while it becomes ineffective in Class-B laser limit (for relatively short resonators). The stabilization effect is further confirmed through direct integration of the dynamical equations.

V.Z. Tronciu, M. Radziunas, Ch. Kürbis, H. Wenzel, A. Wicht, Numerical and experimental investigations of micro-integrated external cavity diode lasers, Optical and Quantum Electronics, 47 (2015), pp. 1459--1464.

M. Radziunas, R. Herrero, M. Botey, K. Staliunas, Far-field narrowing in spatially modulated broad-area edge-emitting semiconductor amplifiers, Journal of the Optical Society of America. B, 32 (2015), pp. 993--1000.
Abstract
We perform a detailed theoretical analysis of the far field narrowing in broad-area edgeemitting semiconductor amplifiers that are electrically injected through the contacts periodically modulated in both, longitudinal and transverse, directions. The beam propagation properties within the semiconductor amplifier are explored by a (1+2)-dimensional traveling wave model and its coupled mode approximation. Assuming a weak field regime, we analyze the impact of different parameters and modulation geometry on the narrowing of the principal far field component.

M. Radziunas, V.Z. Tronciu, E. Luvsandamdin, Ch. Kürbis, A. Wicht, H. Wenzel, Study of micro-integrated external-cavity diode lasers: Simulations, analysis and experiments, IEEE J. Quantum Electron., 51 (2015), pp. 2000408/1--2000408/8.
Abstract
This paper reports the results of numerical and experimental investigations of the dynamics of an external cavity diode laser device composed of a semiconductor laser and a distant Bragg grating, which provides an optical feedback. Due to the influence of the feedback, this system can operate at different dynamic regimes. The traveling wave model is used for simulations and analysis of the nonlinear dynamics in the considered laser device. Based on this model, a detailed analysis of the optical modes is performed, and the stability of the stationary states is discussed. It is shown, that the results obtained from the simulation and analysis of the device are in good agreement with experimental findings.

M. Radziunas, Longitudinal modes of multisection edge-emitting and ring semiconductor lasers, Optical and Quantum Electronics, 47 (2015), pp. 1319--1325.
Abstract
We use the traveling wave model for simulating and analyzing nonlinear dynamics of multisection ring and edge-emitting semiconductor laser devices. We introduce the concept of instantaneous longitudinal optical modes and present an algorithm for their computation. A semiconductor ring laser was considered to illustrate the advantages of the mode analysis.

A. Pimenov, E.A. Viktorov, S.P. Hegarty, T. Habruseva, G. Huyet, D. Rachinskii, A.G. Vladimirov, Bistability and hysteresis in an optically injected two-section semiconductor laser, , 89 (2014), pp. 052903/1--052903/7.
Abstract
The effect of coherenct single frequency injection in two-section semiconductor lasers is studied numerically using a model based on a set of delay differential equations. The existence of bistability between different CW and non-stationary regimes of operation is demonstrated in the case of sufficiently large linewidth enhancement factors.

M. Radziunas, R. Čiegis, A. Mirinavičius, On compact high order finite difference schemes for linear Schrödinger problem on non-uniform meshes, International Journal of Numerical Analysis and Modeling. Wuhan University, Wuhan and Institute for Scientific Computing and Information(ISCI), Edmonton, Alberta. English., 11 (2014), pp. 303--314.

M. Tlidi, K. Staliunas, K. Panajotov, A.G. Vladimirov, M.G. Clerc, Introduction: Localized structures in dissipative media: From optics to plant ecology, Philosophical Transactions of the Royal Society A : Mathematical, Physical & Engineering Sciences, 372 (2014), pp. 20140101/1--20140101/18.
Abstract
We investigate a control of the motion of localized structures of light by means of delay feedback in the transverse section of a broad area nonlinear optical system. The delayed feedback is found to induce a spontaneous motion of a solitary localized structure that is stationary and stable in the absence of feedback. We focus our analysis on an experimentally relevant system namely the Vertical-Cavity Surface-Emitting Laser (VCSEL). In the absence of the delay feedback we present experimental evidence of stationary localized structures in a 80 ?m aperture VCSEL. The spontaneous formation of localized structures takes place above the lasing threshold and under optical injection. Then, we consider the effect of the time-delayed optical feedback and investigate analytically the role of the phase of the feedback and the carrier lifetime on the self-mobility properties of the localized structures. We show that these two parameters affect strongly the space time dynamics of two-dimensional localized structures. We derive an analytical formula for the threshold associated with drift instability of localized structures and a normal form equation describing the slow time evolution of the speed of the moving structure.

A. Pérez-Serrano, J. Javaloyes, S. Balle, Directional reversals and multimode dynamics in semiconductor ring lasers, Physical Review A, 89 (2014), pp. 023818/1--023818/14.
Abstract
We investigate the dynamics of longitudinal modes in quantum-well semiconductor ring lasers by means of a spatio-temporal travelling wave model. We report the existence of a novel multimode instability in such a system that provokes a periodic deterministic directional reversal involving jumps between consecutive longitudinal modes. The switching sequence follows the modal frequencies from blue to red, and every modal jump is accompanied by a reversal of the direction of emission. We characterize and analyze such instability via the bifurcation analysis of the full travelling wave model as well as by performing the linear stability analysis of the monochromatic solutions.

M. Radziunas, R. Čiegis, Effective numerical algorithm for simulations of beam stabilization in broad area semiconductor lasers and amplifiers, Mathematical Modelling and Analysis. Matematinis Modeliavimis ir Analize. The Baltic Journal on Mathematical Applications, Numerical Analysis and Differential Equations, 19 (2014), pp. 627--646.

R.M. Arkhipov, A. Pimenov, M. Radziunas, A.G. Vladimirov, D. Arsenjević, D. Rachinskii, H. Schmeckebier, D. Bimberg, Hybrid mode-locking in edge-emitting semiconductor lasers: Simulations, analysis and experiments, IEEE J. Select. Topics Quantum Electron., 19 (2013), pp. 1100208/1--1100208/6.
Abstract
Hybrid mode-locking in a two section edge-emitting semiconductor laser is studied numerically and analytically using a set of three delay differential equations. In this set the external RF signal applied to the saturable absorber section is modeled by modulation of the carrier relaxation rate in this section. Estimation of the locking range where the pulse repetition frequency is synchronized with the frequency of the external modulation is performed numerically and the effect of the modulation shape and amplitude on this range is investigated. Asymptotic analysis of the dependence of the locking range width on the laser parameters is carried out in the limit of small signal modulation. Our numerical simulations indicate that hybrid mode-locking can be also achieved in the cases when the frequency of the external modulation is approximately twice larger and twice smaller than the pulse repetition frequency of the free running passively mode-locked laser fP . Finally, we provide an experimental demonstration of hybrid mode-locking in a 20 GHz quantum-dot laser with the modulation frequency of the reverse bias applied to the absorber section close to fP =2.

A. Pérez-Serrano, J. Javaloyes, S. Balle, Multi-channel wavelength conversion using four-wave mixing in semiconductor ring lasers, IEEE Phot. Tech. Letter, 25 (2013), pp. 476--479.
Abstract
We theoretically study all-optical simultaneous wavelength conversion of multiple channels by four-wave mixing in semiconductor ring lasers. Locking the semiconductor ring laser to a holding beam allows to achieve large conversion efficiencies with good signal-tonoise ratio in several channels at multi-Gb/s bit rates. Cross-talk between signals, arising from the peculiar four-wave mixing cascade of modes in semiconductor ring lasers and their cross-gain saturation, is studied in detail. We show that it can be controlled by adjusting the intensity of the holding beam, the bias current of the laser and the number, intensity and wavelength of signals that one wants to convert.

A. Pérez-Serrano, J. Javaloyes, S. Balle, Spectral delay algebraic equation approach to broad area laser diodes, IEEE J. Select. Topics Quantum Electron., 19 (2013), pp. 1502808/1--1502808/8.

A. Pimenov, A.G. Vladimirov, S.V. Gurevich, K. Panajotov, G. Huyet, M. Tlidi, Delayed feedback control of self-mobile cavity solitons, Physical Review A, 88 (2013), pp. 053830/1--053830/11.
Abstract
Control of the motion of cavity solitons is one the central problems in nonlinear optical pattern formation. We report on the impact of the phase of the time-delayed optical feedback and carrier lifetime on the self-mobility of localized structures of light in broad area semiconductor cavities. We show both analytically and numerically that the feedback phase strongly affects the drift instability threshold as well as the velocity of cavity soliton motion above this threshold. In addition we demonstrate that non-instantaneous carrier response in the semiconductor medium is responsible for the increase in critical feedback rate corresponding to the drift instability.

M. Radziunas, M. Botey, R. Herrero, K. Staliunas, Intrinsic beam shaping mechanism in spatially modulated broad area semiconductor amplifiers, Applied Physics Letters, 103 (2013), pp. 132101/1--132101/4.
Abstract
We investigate beam shaping in broad area semiconductor amplifiers induced by a periodic modulation of the pump on a scale of several microns. The study is performed by solving numerically a (2+1)-dimensional model for the semiconductor amplifier. We show that, under realistic conditions, the anisotropic gain induced by the pump periodicity can show narrow angular profile of enhanced gain of less than one degree, providing an intrinsic filtering mechanism and eventually improving the spatial beam quality.

A. Wilms, P. Mathé, F. Schulze, Th. Koprucki, A. Knorr, U. Bandelow, Influence of the carrier reservoir dimensionality on electron-electron scattering in quantum dot materials, Phys. Rev. B., 88 (2013), pp. 235421/1--235421/11.
Abstract
We calculated Coulomb scattering rates from quantum dots (QDs) coupled to a 2D carrier reservoir and QDs coupled to a 3D reservoir. For this purpose, we used a microscopic theory in the limit of Born-Markov approximation, in which the numerical evaluation of high dimensional integrals is done via a quasi-Monte Carlo method. Via a comparison of the so determined scattering rates, we investigated the question whether scattering from 2D is generally more efficient than scattering from 3D. In agreement with experimental findings, we did not observe a significant reduction of the scattering efficiency of a QD directly coupled to a 3D reservoir. In turn, we found that 3D scattering benefits from it?s additional degree of freedom in the momentum space.

S. Slepneva, B. Kelleher, B. O'Shaughnessy, S.P. Hegarty, A.G. Vladimirov, G. Huyet, Dynamics of Fourier domain mode-locked lasers, Optics Express, 21 (2013), pp. 19240--19251.

R. Čiegis, A. Mirinavičius, M. Radziunas, Comparison of split step solvers for multidimensional Schrödinger problems, Computational Methods in Applied Mathematics, 13 (2013), pp. 237--250.
Abstract
Hybrid mode-locking in a two section edge-emitting semiconductor laser is studied numerically and analytically using a set of three delay differential equations. In this set the external RF signal applied to the saturable absorber section is modeled by modulation of the carrier relaxation rate in this section. Estimation of the locking range where the pulse repetition frequency is synchronized with the frequency of the external modulation is performed numerically and the effect of the modulation shape and amplitude on this range is investigated. Asymptotic analysis of the dependence of the locking range width on the laser parameters is carried out in the limit of small signal modulation. Our numerical simulations indicate that hybrid mode-locking can be also achieved in the cases when the frequency of the external modulation is approximately twice larger and twice smaller than the pulse repetition frequency of the free running passively mode-locked laser fP . Finally, we provide an experimental demonstration of hybrid mode-locking in a 20 GHz quantum-dot laser with the modulation frequency of the reverse bias applied to the absorber section close to fP =2.

A. Pimenov, V.Z. Tronciu, U. Bandelow, A.G. Vladimirov, Dynamical regimes of multi-stripe laser array with external off-axis feedback, Journal of the Optical Society of America. B, 30 (2013), pp. 1606--1613.
Abstract
We study theoretically the dynamics of a multistripe laser array with an external cavity formed by either a single or two off-axis feedback mirrors, which allow to select a single lateral mode with transversely modulated intensity distribution. We derive and analyze a reduced model of such an array based on a set of delay differential equations taking into account transverse carrier grating in the semiconductor medium. With the help of the bifurcation analysis of the reduced model we show the existence of single and multimode instabilities leading to periodic and irregular pulsations of the output intensity. In particular, we observe a multimode instability leading to a periodic regime with anti-phase oscillating intensities of the two counter-propagating waves in the external cavity. This is in agreement with the result obtained earlier with the help of a 2+1 dimensional traveling wave model.

A. Wilms, D. Breddermann, P. Mathé, Theory of direct capture from two- and three-dimensional reservoirs to quantum dot states, physica status solidi (c), 9 (2012), pp. 1278--1281.

T. Habruseva, S.P. Hegarty, A.G. Vladimirov, A. Pimenov, D. Rachinskii, N. Rebrova, E.A. Viktorov, G. Huyet, Bistable regimes in an optically injected mode-locked laser, Optics Express, 20 (2012), pp. 25572--25583.

M. Lichtner, V.Z. Tronciu, A.G. Vladimirov, Theoretical investigations of striped and non-striped broad area lasers with off-axis feedback, IEEE J. Quantum Electron., 48 (2012), pp. 353--360.

M. Tlidi, E. Averlant, A.G. Vladimirov, K. Panajotov, Delay feedback induces a spontaneous motion of two-dimensional cavity solitons in driven semiconductor microcavities, Physical Review A, 86 (2012), pp. 033822/1--033822/8.

D. Turaev, A.G. Vladimirov, S. Zelik, Long range interaction and synchronization of oscillating dissipative solitons, Physical Review Letters, 108 (2012), pp. 263906/1--263906/5.

M. Radziunas, A.G. Vladimirov, E.A. Viktorov, G. Fiol, H. Schmeckebier, D. Bimberg, Pulse broadening in quantum-dot mode-locked semiconductor lasers: Simulation, analysis and experiments, IEEE J. Quantum Electron., 47 (2011), pp. 935-943.
Abstract
We consider a mode-locked quantum-dot edge-emitting semiconductor laser consisting of a reverse biased saturable absorber and a forward biased amplifying section. To describe the dynamics of this laser we use the traveling wave model taking into account carrier exchange processes between a reservoir and the quantum dots. A comprehensive parameter study is presented and an analysis of mode-locking pulse broadening with an increase of injection current is performed. The results of our theoretical analysis are supported by experimental data demonstrating a strong pulse asymmetry in a monolithic two section quantum dot mode-locked laser.

M. Radziunas, K.-H. Hasler, B. Sumpf, T.Q. Tien, H. Wenzel, Mode transitions in DBR semiconductor lasers: Experiments, mode analysis and simulations, Journal of Physics B: Atomic, Molecular and Optical Physics, 44 (2011), pp. 105401/1--105401/8.
Abstract
The performance of a multisection DBR semiconductor laser emitting around 1060 nm is experimentally and theoretically investigated. Simulations and mode analysis of the traveling wave model including temperature induced changes of the refractive index explain experimentally observed nearly-periodic transitions between neighboring cavity mode determined continuous wave states with increasing injection current.

I. Babushkin, U. Bandelow, A.G. Vladimirov, Rotational symmetry breaking in small-area circular vertical cavity surface emitting lasers, Optics Communications, 284 (2011), pp. 1299--1302.
Abstract
We investigate theoretically the dynamics of three low-order transverse modes in a small-area vertical cavity surface emitting laser. We demonstrate the breaking of axial symmetry of the transverse field distribution in such a device. In particular, we show that if the linewidth enhancement factor is sufficiently large dynamical regimes with broken axial symmetry can exist up to very high diffusion coefficients  10 um^2/ns.

J.-E. Kim, M.-R. Dachner, A. Wilms, M. Richter, E. Malic, Microscopic study of relaxation oscillations in quantum-dot VCSELs, Photonics and Nanostructures - Fundamentals and Applications, 9 (2011), pp. 337-344.

N. Rebrova, G. Huyet, D. Rachinskii, A.G. Vladimirov, Optically injected mode-locked laser, , 83 (2011), pp. 066202/1-066202/8.

M. Radziunas, K. Staliunas, Spatial ``rocking'' in broad-area semiconductor lasers, Europhysics Letters, 95 (2011), pp. 14002/1--14002/6.
Abstract
The spatial “rocking” is a dynamical effect converting a phase-invariant oscillatory system into a phase-bistable one, where the average phase of the system locks to one of two values differing by $pi$. We demonstrate theoretically the spatial rocking in experimentally accessible and practically relevant systems -- the broad area semiconductor lasers. By numerical integration of the laser model equations we show the phase bistability of the optical fields and explore the bistability area in parameter space. We also predict the spatial patterns, such as phase domain walls and phase solitons, which are characteristic for the phase-bistable spatially extended pattern forming systems.

V.Z. Tronciu, C. Mirasso, P. Colet, M. Hamacher, M. Benedetti, V. Vercesi, V. Annovazzi-Lodi, Chaos generation and synchronization using an integrated source with an air gap, IEEE J. Quantum Electron., 46 (2010), pp. 1840--1846.

V.Z. Tronciu, Chaos communication using semiconductor lasers subject to different kinds of optical feedback, Moldavian Journal of the Physical Sciences, 9 (2010), pp. 50-69.

A.G. Vladimirov, U. Bandelow, G. Fiol, D. Arsenijević, M. Kleinert, D. Bimberg, A. Pimenov, D. Rachinskii, Dynamical regimes in a monolithic passively mode-locked quantum dot laser, Journal of the Optical Society of America. B, 27 (2010), pp. 2102-2109.

R. Čiegis, M. Radziunas, Effective numerical integration of traveling wave model for edge-emitting broad-area semiconductor lasers and amplifiers, Mathematical Modelling and Analysis. Matematinis Modeliavimis ir Analize. The Baltic Journal on Mathematical Applications, Numerical Analysis and Differential Equations, 15 (2010), pp. 409--430.
Abstract
We consider a system of 1+2 dimensional partial differential equations which describes dynamics of edge-emitting broad area semiconductor lasers and amplifiers. The given problem is defined on the unbounded domain. After truncating this domain and defining an auxiliary $1+1$ dimensional linear Schrodinger problem supplemented with different artificial boundary conditions, we propose an effective strategy allowing to get a solution of the full problem with a satisfactory precision in a reasonable time. For further speed up of the numerical integration, we develop a parallel version of the algorithm

M.-R. Dachner, E. Malic, M. Richter, A. Carmele, J. Kabuss, A. Wilms, J.-E. Kim, G. Hartmann, J. Wolters, U. Bandelow, A. Knorr, Theory of carrier and photon dynamics in quantum dot light emitters, physica status solidi (b), 247 (2010), pp. 809--828.
Abstract
We present a microscopic theory describing the charge carrier and light emission dynamics in quantum dot (QD) light emitters. The theory covers non-classical light emission (fluorescence and Raman emission) in the low carrier injection limit as well as laser emission and pulse amplification in the high carrier injection limit. The theoretical approach is based on QD Bloch equations including microscopically calculated Coulomb and electron-phonon scattering rates between bound QD, continuous wetting layer (WL) and bulk states. In the low carrier density limit, multi-phonon relaxation is the dominant process, while at high charge carrier densities, Coulomb scattering dominates the dynamics. Using an equation of motion approach, we address (i) time-resolved fluorescence and Raman emission, (ii) electrical injection and charge carrier transfer from bulk into WL and QD states, (iii) single photon emission and (iv) gain dynamics of QD amplifiers and lasing dynamics in QD vertical-cavity surface-emitting lasers (VCSELs) at high injection currents.

CH. Fiebig, V.Z. Tronciu, M. Lichtner, H. Wenzel, K. Paschke, Experimental and numerical study of distributed Bragg reflector tapered lasers, Applied Physics B: Lasers and Optics, 99 (2010), pp. 209--214.
Abstract
We report results on experimental and numerical investigations of the output characteristics of edge-emitting distributed Bragg reflector tapered diode lasers emitting around 980 nm. The experimental results are well described by the Traveling Wave model which is extended by a parametrical heating model. Dynamic instabilities occur due to different thermally induced refractive index changes.

G. Fiol, D. Arsenijević, D. Bimberg, A.G. Vladimirov, M. Wolfrum, E.A. Viktorov, P. Mandel, Hybrid mode-locking in a 40 GHz monolithic quantum dot laser, Applied Physics Letters, 96 (2010), pp. 011104/1--011104/3.

J.-E. Kim, E. Malic, M. Richter, A. Wilms, A. Knorr, Maxwell--Bloch equation approach for describing the microscopic dynamics of quantum-dot surface-emitting structures, IEEE J. Quantum Electron., 46 (2010), pp. 1115--1126.

M. Schulz-Ruhtenberg, I. Babushkin, N.A. Loiko, Th. Ackemann, K. Huang, Polarization properties in the transition from below to above lasing threshold in broad-area vertical-cavity surface-emitting lasers, Physical Review A, 81 (2010), pp. 023819/1--023819/11.
Abstract
For highly divergent emission of broad-area vertical-cavity surface-emitting lasers (VCSELs) a rotation of the polarization direction by up to 90 degrees occurs when the pump rate approaches the lasing threshold. Well below threshold the polarization is parallel to the direction of the transverse wave vector and is determined by the transmissive properties of the Bragg reflectors that form the cavity mirrors. In contrast, near-threshold and above-threshold emission is more affected by the reflective properties of the reflectors and is predominantly perpendicular to the direction of transverse wave vectors. Two qualitatively different types of polarization transition are demonstrated: an abrupt transition, where the light polarization vanishes at the point of the transition, and a smooth one, where it is significantly nonzero during the transition.

I. Babushkin, Non-Poissonian statistics in an optical analog of quantum billiard with perfectly square boundaries, Physics Letters A, 374 (2010), pp. 896--900.
Abstract
We study deviation from the Poissonian statistics of the frequency spacing distribution, appearing due to coupling of polarizational and transverse degrees of freedom in a perfectly square vertical cavity surface emitting laser. The deviation can be controlled by strength of the intracavity anisotropy and its alignment to the device boundaries.

M. Wolfrum, S. Yanchuk, A multiple time scale approach to the stability of external cavity modes in the Lang--Kobayashi system using the limit of large delay, SIAM Journal on Applied Dynamical Systems, 9 (2010), pp. 519--535.

V.Z. Tronciu, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, Improving the stability of distributed-feedback tapered master-oscillator power-amplifiers, Optical and Quantum Electronics, 41 (2009), pp. 531--537.
Abstract
We report theoretical results on the wavelength stabilization in distributed-feedback master-oscillator power-amplifiers which are compact semiconductor laser devices capable of emitting a high brilliance beam at an optical power of several Watts. Based on a traveling wave equation model we calculate emitted optical power and spectral maps in dependence on the pump of the power amplifier. We show that a proper choice of the Bragg grating type and coupling coefficient allows to optimize the laser operation, such that for a wide range of injection currents the laser emits a high intensity continuous wave beam.

A.G. Vladimirov, A. Pimenov, D. Rachinskii, Numerical study of dynamical regimes in a monolithic passively mode locked semiconductor laser, IEEE J. Quantum Electron., 45 (2009), pp. 462--468.

R. Čiegis, I. Laukaitytė, M. Radziunas, Numerical algorithms for Schrödinger equation with artificial boundary conditions, Numerical Functional Analysis and Optimization. An International Journal, 30 (2009), pp. 903--923.
Abstract
We consider a one-dimensional linear Schrödinger problem defined on an infinite domain and approximated by the Crank-Nicolson type finite difference scheme. To solve this problem numerically we restrict the computational domain by introducing the reflective, absorbing or transparent artificial boundary conditions. We investigate the conservativity of the discrete scheme with respect to the mass and energy of the solution. Results of computational experiments are presented and the efficiency of different artificial boundary conditions is discussed.

I.V. Ermakov, V.Z. Tronciu, P. Colet, C.R. Mirasso, Controlling the unstable emission of a semiconductor laser subject to conventional optical feedback with a filtered feedback branch, Optics Express, 17 (2009), pp. 8749--8755.

A. Jechow, M. Lichtner, R. Menzel, M. Radziunas, D. Skoczowsky, A.G. Vladimirov, Stripe-array diode-laser in an off-axis external cavity: Theory and experiment, Optics Express, 17 (2009), pp. 19599--19604.
Abstract
Stripe-array diode lasers naturally operate in an anti-phase supermode. This produces a sharp double lobe far field at angles $pm alpha$ depending on the period of the array. In this paper a 40 emitter gain guided stripe-array laterally coupled by off-axis filtered feedback is investigated experimentally and numerically. We predict theoretically and confirm experimentally that at doubled feedback angle $2 alpha$ a stable higher order supermode exists with twice the number of emitters per array period. The theoretical model is based on time domain traveling wave equations for optical fields coupled to the carrier density equation taking into account diffusion of carriers. Feedback from the external reflector is modeled using Fresnel integration.

M. Spreemann, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, Measurement and simulation of distributed-feedback tapered master-oscillator power-amplifiers, IEEE J. Quantum Electron., 45 (2009), pp. 609--616.

M. Radziunas, V.Z. Tronciu, U. Bandelow, M. Lichtner, M. Spreemann, H. Wenzel, Mode transitions in distributed-feedback tapered master-oscillator power-amplifier: Theory and experiments, Optical and Quantum Electronics, 40 (2008), pp. 1103-1109.
Abstract
Theoretical and experimental investigations have been carried out to study the spectral and spatial behavior of monolithically integrated distributed-feedback tapered master-oscillators power-amplifiers emitting around 973 nm. Introduction of self and cross heating effects and the analysis of longitudinal optical modes allows us to explain experimental results. The results show a good qualitative agreement between measured and calculated characteristics.

V.Z. Tronciu, I.V. Ermakov, P. Colet, C.R. Mirasso, Chaotic dynamics of a semiconductor laser with double cavity feedback: Applications to phase shift keying modulation, Optics Communications, 281 (2008), pp. 4747--4752.

V.Z. Tronciu, C.R. Mirasso, P. Colet, Chaos-based communications using on-off phase shift keying method, Moldavian Journal of the Physical Sciences, 7 (2008), pp. 343--349.

V.Z. Tronciu, C.R. Mirasso, P. Colet, Chaos-based communications using semiconductor lasers subject to feedback from an integrated double cavity, Journal of Physics B: Atomic, Molecular and Optical Physics, 41 (2008), pp. 155401/1--155401/8.

S. Yanchuk, K.R. Schneider, O. Lykova, Amplitude synchronization in a system of two coupled semiconductor lasers, Ukrainian Mathematical Journal, 60 (2008), pp. 426-435.

R. Čiegis, M. Radziunas, M. Lichtner, Numerical algorithms for simulation of multisection lasers by using traveling wave model, IEEE J. Select. Topics Quantum Electron., 13 (2008), pp. 327-348.

M. Radziunas, A. Glitzky, U. Bandelow, M. Wolfrum, U. Troppenz, J. Kreissl, W. Rehbein, Improving the modulation bandwidth in semiconductor lasers by passive feedback, IEEE J. Select. Topics Quantum Electron., 13 (2007), pp. 136--142.

O.V. Ushakov, N. Korneyer, M. Radziunas, H.-J. Wünsche, F. Henneberger, Excitability of chaotic transients in a semiconductor laser, Europhysics Letters, 79 (2007), pp. 30004/1--30004/5.

E.A. Viktorov, P. Mandel, M. Kuntz, G. Fiol, D. Bimberg, A.G. Vladimirov, M. Wolfrum, Stability of the modelocked regime in quantum dot lasers, Applied Physics Letters, 91 (2007), pp. 231116/1-231116/3.

M. Radziunas, Numerical bifurcation analysis of the traveling wave model of multisection semiconductor lasers, Optical and Quantum Electronics, 213 (2006), pp. 98--112.

S. Yanchuk, A. Stefanski, T. Kapitaniak, J. Wojewoda, Dynamics of an array of mutually coupled semiconductor lasers, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 73 (2006), pp. 016209/1--016209/7.

B. Hüttl, H. Kaiser, Ch. Kindel, S. Fidorra, W. Rehbein, H. Stolpe, G. Sahin, U. Bandelow, M. Radziunas, A. Vladimirov, H. Heidrich, Experimental investigations on the suppression of Q-switching in monolithic 40 GHz mode-locked semiconductor lasers, Applied Physics Letters, 88 (2006), pp. 221104/1--221104/3.

M. Nizette, D. Rachinskii, A. Vladimirov, M. Wolfrum, Pulse interaction via gain and loss dynamics in passive mode-locking, Physica D. Nonlinear Phenomena, 218 (2006), pp. 95--104.

T. Perez, M. Radziunas, H.-J. Wünsche, C.R. Mirasso, F. Henneberger, Synchronization properties of two coupled multisection semiconductor lasers emitting chaotic light, IEEE Phot. Tech. Letter, 18 (2006), pp. 2135-2137.

D.I. Rachinskii, A. Vladimirov, U. Bandelow, B. Hüttl, R. Kaiser, Q-switching instability in a mode-locked semiconductor laser, Journal of the Optical Society of America. B, 23 (2006), pp. 663--670.

V.Z. Tronciu, H.-J. Wünsche, M. Wolfrum, M. Radziunas, Semiconductor laser under resonant feedback from a Fabry--Perot resonator: Stability of continuous-wave operation, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 73 (2006), pp. 046205/1--046205/7.

E. Viktorov, P. Mandel, A. Vladimirov, U. Bandelow, A model for mode-locking in quantum dot lasers, Applied Physics Letters, 88 (2006), pp. 201102/1--201102/3.

U. Bandelow, M. Radziunas, A. Vladimirov, B. Hüttl, R. Kaiser, 40 GHz Mode-locked semiconductor lasers: Theory, simulations and experiment, Optical and Quantum Electronics, 38 (2006), pp. 495--512.

TH. Koprucki, M. Baro, U. Bandelow, Th. Tien, F. Weik, J.W. Tomm, M. Grau, M.-Ch. Amann, Electronic structure and optoelectronic properties of strained InAsSb/GaSb multiple quantum wells, Applied Physics Letters, 87 (2005), pp. 181911/1--181911/3.

A.G. Vladimirov, D. Turaev, Model for passive mode locking in semiconductor lasers, Physical Review A, 72 (2005), pp. 033808/1-033808/13.

S. Yanchuk, Properties of stationary states of delay equations with large delay and applications to laser dynamics, Mathematical Methods in the Applied Sciences, 28 (2005), pp. 363--377.

A.G. Vladimirov, D.V. Turaev, G. Kozyreff, Delay differential equations for mode-locked semiconductor lasers, , 29 (2004), pp. 1221--1223.

A.G. Vladimirov, D.V. Turaev, A new model for a mode-locked semiconductor laser, Radiophysics and Quantum Electronics, 47 (2004), pp. 769--776.

S. Bauer, J. Kreissl, M. Radziunas, H.-J. Wünsche, F. Henneberger, J. Sieber, M. Sartorius, O. Brox, Nonlinear dynamics of semiconductor lasers with active optical feedback, Phys. Rev. E (3), 69 (2004), pp. 016206/1--016206/10.

J. Sieber, M. Radziunas, K.R. Schneider, Dynamics of multisection semiconductor lasers, Mathematical Modelling and Analysis. Matematinis Modeliavimis ir Analize. The Baltic Journal on Mathematical Applications, Numerical Analysis and Differential Equations, 9 (2004), pp. 51--66.

J. Sieber, L. Recke, K.R. Schneider, Dynamics of multisection semiconductor lasers, Journal of Mathematical Sciences (New York), 124 (2004), pp. 5298--5309.

K.R. Schneider, S. Yanchuk, L. Recke, Dynamics of two mutually coupled semiconductor lasers: Instantaneous coupling limit, Phys. Rev. E (3), 69 (2004), pp. 056221/1--056221/12.

V. Tronciu, Investigation of self-pulsation and excitability of tandem blue lasers, AIUB Journal of Science and Engineering, 3 (2004), pp. 7--10.

O. Brox, S. Bauer, M. Radziunas, M. Wolfrum, J. Sieber, J. Kreissl, B. Sartorius, H.-J. Wünsche, High-frequency pulsations in DFB-lasers with amplified feedback, Numerical Functional Analysis and Optimization. An International Journal, 39 (2003), pp. 1381--1387.

B. Krauskopf, K.R. Schneider, J. Sieber, S. Wieczorek, M. Wolfrum, Excitability and self-pulsations near homoclinic bifurcations in semiconductor laser systems, IEEE J. Quantum Electron., 215 (2003), pp. 367--379.

H.-J. Wünsche, M. Radziunas, S. Bauer, O. Brox, B. Sartorius, Simulation of phase-controlled mode-beating lasers, IEEE J. Select. Topics Quantum Electron., 9 (2003), pp. 857--864.

U. Bandelow, R. Hünlich, Th. Koprucki, Simulation of static and dynamic properties of edge-emitting multiple-quantum-well lasers, IEEE J. Select. Topics Quantum Electron., 9 (2003), pp. 798--806.

A.G. Vladimirov, G. Kozyreff, P. Mandel, Synchronization of weakly stable oscillators and semiconductor laser arrays, Europhysics Letters, 61 (2003), pp. 613--619.

A.G. Vladimirov, G. Kozyreff, P. Mandel, Synchronization of weakly stable oscillators and semiconductor laser arrays, Europhysics Letters, 61 (2003), pp. 613--619.

H.-J. Wünsche, O. Brox, M. Radziunas, F. Henneberger, Excitability of a semiconductor laser by a two-mode homoclinic bifurcation, Physical Review Letters, 88 (2002), pp. 023901/1--023901/4.

D. Turaev, M. Wolfrum, Instabilities of lasers with moderately delayed optical feedback, IEEE J. Quantum Electron., 213 (2002), pp. 127--138.

U. Bandelow, M. Radziunas, J. Sieber, M. Wolfrum, Impact of gain dispersion on the spatio-temporal dynamics of multisection lasers, IEEE J. Quantum Electron., 37 (2001), pp. 183--188.

M. Möhrle, B. Sartorius, C. Bornholdt, S. Bauer, O. Brox, A. Sigmund, R. Steingräber, M. Radziunas, H.-J. Wünsche, Detuned grating multi-section-RW-DFB lasers for high speed optical signal processing, IEEE J. Select. Topics Quantum Electron., 7 (2001), pp. 217--223.

V. Tronciu, H.-J. Wünsche, J. Sieber, K.R. Schneider, Dynamics of single mode semiconductor lasers with passive dispersive reflectors, , 182 (2000), pp. 221--228.

M. Radziunas, H.-J. Wünsche, B. Sartorius, O. Brox, D. Hoffmann, K.R. Schneider, D. Marcenac, Modeling self-pulsating DFB-lasers with an integrated phase tuning section, IEEE J. Quantum Electron., 36 (2000), pp. 1026--1034.

L. Mertenskötter, M. Kantner, Bayesian estimation of laser linewidth from delayed self-heterodyne measurements, Conference on Structural Nonlinear Dynamics and Diagnosis (CSNDD 2023), Marrakesh, Morocco, May 15 - 17, 2024, M. Belhaq, ed., 301 of Springer Proceedings in Physics, Springer, Singapur, 2024, pp. 269--279, DOI 10.1007/978-981-99-7958-5_21 .
Abstract
We present a statistical inference approach to estimate the frequency noise characteristics of ultra-narrow linewidth lasers from delayed self-heterodyne beat note measurements using Bayesian inference. Particular emphasis is on estimation of the intrinsic (Lorentzian) laser linewidth. The approach is based on a statistical model of the measurement process, taking into account the effects of the interferometer as well as the detector noise. Our method therefore yields accurate results even when the intrinsic linewidth plateau is obscured by detector noise. The regression is performed on periodogram data in the frequency domain using a Markov-chain Monte Carlo method. By using explicit knowledge about the statistical distribution of the observed data, the method yields good results already from a single time series and does not rely on averaging over many realizations, since the information in the available data is evaluated very thoroughly. The approach is demonstrated for simulated time series data from a stochastic laser rate equation model with 1 / f-type non-Markovian noise.

L. Ermoneit, B. Schmidt, J. Fuhrmann, Th. Koprucki, L.R. Schreiber, M. Kantner, Simulation of single-electron shuttling for spin-qubit transport in a SiGe quantum bus, in: Book of Abstracts of the International Workshop on Computational Nanotechnology 2023 (IWCN 2023), X. Orios Plaedvall, G. Abadal Berini, X. Cartoixà Soler, A. Cummings, C.F. Destefani, D. Jiménez Jiménez, J. Mart'in Mart'inez, R. Rodr'iguez Mart'inez, A. Benali, eds., pp. 88-89.

M. Kantner, L. Mertenskötter, Estimation of frequency noise characteristics and data-driven modeling of narrow-linewidth semiconductor lasers, in: 23nd International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2023), P. Bardella, A. Tibaldi, eds., IEEE, 2023, pp. 55--56, DOI 10.1109/NUSOD59562.2023.10273522 .
Abstract
The design of narrow-linewidth lasers requires stochastic laser models providing a realistic description of the noise in the device. We present a statistical inference approach to extract the frequency noise characteristics and model parameters of narrow-linewidth lasers from delayed self-heterodyne beat note experiments. By exploiting prior knowledge about the statistical distribution of the measurement data, accurate estimates of the parameters of the free running laser can be achieved even in the presence of considerable detector noise. The approach is demonstrated for simulated time series data using a stochastic laser rate equation model including 1/ftype noise.

M. Kantner, L. Mertenskötter, Wiener-filter enhanced estimation of the intrinsic laser linewidth from delayed self-heterodyne beat note measurements, in: 2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC), IEEE, 2023, pp. 88--89, DOI 10.1109/CLEO/Europe-EQEC57999.2023.10232191 .
Abstract
Narrow-linewidth lasers exhibiting low phase noise are core elements of coherent optical communication systems, gravitational wave interferometers and emerging quantum technologies (e.g., optical atomic clocks, matter-wave interferometers, ion-trap quantum-computers etc.). For many of these applications, the performance depends critically on the laser's intrinsic (Lorentzian) linewidth [1], which is typically obscured by additional 1/f-like technical noise. Because of this so-called flicker noise, the laser linewidth alone is not a well-defined quantity and needs to be specified for a given measurement time. For a detailed characterization of the frequency noise exhibited by the laser, the measurement of the frequency noise power spectral density (FN-PSD) is required.

M. Radziunas, E. Kuhn, H. Wenzel, B. King, P. Crump, Calculation of optical modes in large emission area photonic crystal surface-emitting lasers, in: 23nd International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2023), P. Bardella, A. Tibaldi, eds., IEEE, 2023, pp. 89--90, DOI 10.1109/NUSOD59562.2023.10273475 .
Abstract
We discuss numerical challenges in constructing and resolving spectral problems for photonic crystal surface-emitting lasers with large (up to several mm 2 ) emission area. We show that finite difference schemes with moderate and large domain discretization steps provide sufficient accuracy of several major (lowest-threshold) modes of particular device designs.

A.V. Kovalev, K.M. Grigorenko, S. Slepneva, N. Rebrova, A.G. Vladimirov, G. Huyet, E.A. Viktorov, Bifurcation bridges in mode-locked frequency-swept feedback lasers, in: 2022 International Conference Laser Optics (ICLO), Saint Petersburg, Russian Federation, 2022, IEEE, 2022, pp. 1-1, DOI 10.1109/ICLO54117.2022.9839784 .
Abstract
We describe and explain the periodic mode-locked regime and its mechanisms of occurrence in a frequency swept SG-DBR laser source with continuous optical feedback. We propose that mode-locked operation results from the resonant perturbation of bridges of periodic solutions existing in a non-swept system with feedback.

M. Kantner, L. Mertenskötter, Data-driven modeling of non-Markovian noise in semiconductor lasers, in: 22nd International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), Turin, Italy, 2022, J. Piprek, P. Bardella, eds., IEEE, 2022, pp. 57--58, DOI 10.1109/NUSOD54938.2022.9894788 .
Abstract
Non-Markovian noise degrades the coherence properties of semiconductor lasers and contributes significantly to broadening of the linewidth. Since modeling of such colored noise systems from first principles is not accessible, we aim for a data-driven modeling approach in which a system of stochastic rate equations shall be reconstructed from time series data.

M. Radziunas, Steady states in dynamical semiconductor laser models and their analysis, in: 2022 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), Turin, Italy, 2022, J. Piprek, P. Bardella, eds., IEEE, 2022, pp. 49--50, DOI 10.1109/NUSOD54938.2022.9894775 .
Abstract
We present an algorithm for calculating steady states in the dynamic PDE model for SLs admitting gain compression, spatial hole burning, and multilevel carrier rate equations. Presented example simulations rely on 1(time)+1(space)--dimensional traveling-wave- and Lang--Kobayashi-type models.

A. Roche, U. Gowda, A. Kovalev, E. Viktorov, A. Pimenov, A.G. Vladimirov, M. Marconi, M. Giudici, G. Huyet, S. Slepneva, Defect mediated turbulence in a long laser, in: Real-time Measurements, Rogue Phenomena, and Single-Shot Applications VI, D.R. Solli, G. Herink, S. Bielawski, eds., 11671 of Proceedings of SPIE, SPIE. Digital Library, 2021, pp. 116710D/1--116710D/6, DOI 10.1117/12.2578727 .
Abstract
In this paper, we experimentally and theoretically analyse the formation and interaction of dark solitons in a long laser. The laser includes a semiconductor optical amplifier (SOA), centred around 1300nm, an intracavity filter and a fibre cavity whose length can vary from 20m to 20km. Near the lasing threshold the laser exhibits slowly evolving power dropouts the circulate the cavity. These dropouts are associated with the formation of Nozaki-Bekki Holes (NBH), also referred to as dark solitons. We observe both experimentally and numerically that the core of these holes exhibit chaotic dynamics and emit short light pulses. These pulses are found to be blue shifted with respect to the frequency of the dark solitons and therefore travel with a faster group velocity. These pulses are strongly damped, as they are detuned with respect to the filter transmission, but they may lead to the creation of new dark solitons. These pulses also play a major role in the development of optical turbulence when the filter is set at a frequency above 1310nm. In this case, the laser displays numerous dark solitons per round trip and the fast travelling pulses act as an interaction between the solitons, which can lead to the development of defect mediated turbulence.

A. Roche, U. Gowda, A. Kovalev, E. Viktorov, A. Pimenov, A.G. Vladimirov, M. Marconi, M. Giudici, G. Huyet, S. Slepneva, The formation of localised structures from the turn on transient of a long laser, in: Physics and Simulation of Optoelectronic Devices XXIX, B. Witzigmann, M. Osiński, Y. Arakawa, eds., 11680 of Proceedings of SPIE, SPIE Digital Library, 2021, pp. 116800N/1--116800N/6, DOI 10.1117/12.2578648 .

A. Zeghuzi, J.-P. Koester, M. Radziunas, H. Christopher, H. Wenzel, A. Knigge, Narrow lateral far field divergence obtained with spatially modulated broad-area lasers, in: 2021 27th International Semiconductor Laser Conference (ISLC), IEEE Xplore, IEEE, 2021, pp. 1--2, DOI 10.1109/ISLC51662.2021.9615888 .

A. Roche, U. Gowda, A. Pimenov, A.V. Kovalev, M. Marconi, M. Giudici, E.A. Viktorov, A.G. Vladimirov, G. Huyet, S. Slepneva, Turn on transient in a long cavity laser, in: Physics and Simulation of Optoelectronic Devices XXVII, B. Witzigmann, M. Osiński, Y. Arakawa, eds., 11274 of Proceedings of SPIE, SPIE Digital Library, 2020, pp. 112740L/1--112740L/6, DOI 10.1117/12.2545965 .
Abstract
In this paper we study, both experimentally and theoretically, the turn on transient dynamics observed in a long (20m) cavity laser. The laser consists of a ring cavity based on a single mode fiber with unidirectional propagation of light. The gain is provided by a semiconductor optical amplifier (SOA) centered around 1300nm and wavelength selection is provided by a tunable narrow transmission bandwidth Fabry-Perot filter. At high bias current and when the filter transmission sets the laser to operate in an anomalous dispersion regime, the laser exhibits only chaotic oscillations, while in a normal dispersion regime, the laser can exhibit stable operation. At a bias current close to the threshold the laser always exhibits multiple dropouts. In order to record the lasing build up dynamics, the bias current driven to the SOA is periodically switched from the off-state to a high current level. The lasing build up occurs at each roundtrip via a step-wise increase of the laser intensity. The laser intensity is widely oscillating during the first steps and approaches a stationary state after a large number of roundtrips. Recording of the phase evolution of the electric field during each step demonstrates the linewidth narrowing at each subsequent roundtrip. Theoretically, we describe the system by a set of delay differential equations and observe similar behavior. While typically a semiconductor laser exhibits relaxation oscillations before reaching the stable lasing regime, which is associated with class B lasers, our study shows that the long cavity laser demonstrates a different mechanism of lasing build up.

G. Garre--Werner, J.J. Montiel--Ponsoda, V. Raab, G. Safont, C. Brée, M. Radziunas, C. Cojocaru, K. Staliunas, 1 kW cw fiber-coupled diode laser with enhanced brightness, in: High-Power Diode Laser Technology XVIII, M.S. Zediker, ed., 11262 of Proceedings of SPIE, SPIE, San Francisco, 2020, pp. 1126202/1--1126202/9, DOI 10.1117/12.2546086 .
Abstract
We developed a 1kW cw fiber-coupled diode laser at 9XX nm by using beam combining of eight high power diode laser bars. To achieve beam combining, we employ Lyot-filtered optical reinjection from an external cavity, which forces lasing of the individual diode laser bars on intertwined frequency combs with overlapping envelopes and enables a high optical coupling efficiency. Unlike other spectral beam combining techniques that are based on the use of grating elements, this technique is insensitive to the thermal drift of the laser diodes. In addition to this, the FWHM spectral width at 1 kW output power is only around 7 nm, which is convenient for wavelength sensitive applications such as pumping.

U. Gowda, A. Roche, S. Slepneva, A. Pimenov, E.A. Viktorov, A.G. Vladimirov, G. Huyet, Stability of a long cavity laser, in: Real-time Measurements, Rogue Phenomena, and Single-Shot Applications V, D.R. Solli, G. Herink, S. Bielawski, eds., 11265 of Proceedings of SPIE, SPIE Digital Library, 2020, pp. 112650F/1--112650F/6, DOI 10.1117/12.2545916 .
Abstract
In this paper, we will discuss the properties of long cavity frequency sweeping lasers and demonstrate various scenarios of coherence deterioration in such lasers. The long cavity lasers are known to demonstrate a rich variety of dynamical regimes including the formation of localised structures and transition to turbulence. The interest to frequency sweeping long cavity lasers has recently increased due to their application for imaging and sensing. For these applications, the stability of the laser is an important parameter as it directly influences its coherence and therefore, the quality of the obtained images.1 Our laser consists of a fiber based ring cavity resonator including a semiconductor optical amplifier as a gain medium and a Fabry-Perot tunable filter. Experimentally, we considered different laser configurations which has allowed us to study the influence of the cavity length, frequency sweeping speed and the detuning. We considered the dynamical regimes of the laser operating at a static (fixed output frequency) and quasi static regimes. The study shows that the laser can be stable or unstable and demonstrate localised structures stable over multiple roundtrips. We also show the connection of the dynamics observed in the static, quasi-static and synchronisation regimes of long cavity lasers. Numerically, we used a model based on a system of delayed differential equations. The numerical simulation showed excellent agreement with the experimental data. We also show the formation of dark pulses, both periodic and nonperiodic, and showed that they are closely connected to Nozaki-Bekki holes previously predicted in the complex Ginzburg-Landau equation.

M. Kolarczik, F. Böhm, U. Woggon, N. Owschimikow, A. Pimenov, M. Wolfrum, A.G. Vladimirov, S. Meinecke, B. Lingnau, L. Jaurigue, K. Lüdge, Coherent and incoherent dynamics in quantum dots and nanophotonic devices, in: Semiconductor Nanophotonics, M. Kneissl, A. Knorr, S. Reitzenstein, A. Hoffmann, eds., 194 of Springer Series in Solid-State Sciences, Springer, Cham, 2020, pp. 91--133, DOI 10.1007/978-3-030-35656-9_4 .
Abstract
The interest in coherent and incoherent dynamics in novel semiconductor gain media and nanophotonic devices is driven by the wish to understand the optical gain spectrally, dynamically, and energetically for applications in optical amplifiers, lasers or specially designed multi-section devices. This chapter is devoted to the investigation of carrier dynamics inside nanostructured gain media as well as to the dynamics of the resulting light output. It is structured into two parts. The first part deals with the characterization of ultrafast and complex carrier dynamics via the optical response of the gain medium with pump-probe methods, two-color four-wave mixing setups and quantum-state tomography. We discuss the optical nonlinearities resulting from light-matter coupling and charge carrier interactions using microscopically motivated rate-equation models. In the second part, nanostructured mode-locked lasers are investigated, with a focus on analytic insights about the regularity of the pulsed light emission. A method for efficiently predicting the timing fluctuations is presented and used to optimize the device properties. Finally, one specific design of a mode-locked laser with tapered gain section is discussed which draws the attention to alternative ways of producing very stable and high intensity laser pulses.

J.--P. Köster, M. Radziunas, A. Zeghuzi, H. Wenzel, A. Knigge, Traveling wave model-based analysis of tapered broad-area lasers, in: Physics and Simulation of Optoelectronic Devices XXVIII, B. Witzigmann, M. Osiński, Y. Arakawa, eds., 11274 of Proceedings of SPIE, SPIE, San Francisco, 2020, pp. 112740I/1--112740I/10, DOI 10.1117/12.2537015 .
Abstract
We present simulation results showing the impact of a longitudinal linearly varying electrical contact width on intra-cavity intensity, carrier density and temperature distributions of broad-area lasers. In addition, the impact of index guiding trenches on these internal distributions is investigated. The simulations were performed using a time-dependent traveling wave model which takes all relevant physical effects into account. We show that a tapered contact area results in a reduced longitudinal intensity inhomogeneity as well as longitudinal spatial hole burning, at the cost of an increased temperature towards the front facet. Index guiding trenches were found to effectively prevent lateral intensity modulation as well as lateral carrier accumulation near the contact edges at the front facet.

U. Bandelow, M. Radziunas, A. Zeghuzi, H.-J. Wünsche, H. Wenzel, Dynamics in high-power diode lasers, in: Semiconductor Lasers and Laser Dynamics IX, M. Sciamanna, R. Michalzik, K. Panajotov, S. Höfling, eds., 11356 of Proceedings of SPIE, 2020, pp. 113560W/1--113560W/14, DOI 10.1117/12.2559175 .
Abstract
High-power broad-area diode lasers (BALs) exhibit chaotic spatio-temporal dynamics above threshold. Under high power operation, where they emit tens of watts output, large amounts of heat are generated, with significant impact on the laser operation. We incorporate heating effects into a dynamical electro-optical (EO) model for the optical field and carrier dynamics along the quantum-well active zone of the laser. Thereby we effectively couple the EO and heat-transport (HT) solvers. Thermal lensing is included by a thermally-induced contribution to the index profile. The heat sources obtained with the dynamic EO-solver exhibit strong variations on short time scales, which however have only a marginal impact on the temperature distribution. We consider two limits: First, the static HT-problem, with time-averaged heat sources, which is solved iteratively together with the EO solver. Second, under short pulse operation the thermally induced index distribution can be obtained by neglecting heat flow. Although the temperature increase is small, a waveguide is introduced here within a few-ns-long pulse resulting in significant near field narrowing. We further show that a beam propagating in a waveguide structure utilized for BA lasers does not undergo filamentation due to spatial holeburning. Moreover, our results indicate that in BALs a clear optical mode structure is visible which is neither destroyed by the dynamics nor by longitudinal effects.

M. Radziunas, D.M. Kane, Semiconductor laser with delayed optical feedback -- What simulations tell us that we didn't know, in: 14th Pacific Rim Conference on Lasers and Electro-Optics (CLEO PR 2020), OSA Technical Digest, Optical Society of America, Washington, 2020, pp. C4C_4/1--C4C_4/2, DOI 10.1364/CLEOPR.2020.C4C_4 .
Abstract
Comprehensive numerical simulations of a semiconductor laser with optical feedback system showing the impact of key laser parameters on dynamical mapping are reported. These raise new opportunities for optimising such systems for their key applications.

M. Radziunas, J. Montiel-Ponsoda, G. Garre-Werner, V. Raab, Simulation of cascaded polarization-coupled systems of broad-area semiconductor lasers, in: Proceedings of the 20th International Conference on Numerical Simulation of Optoelectronic Devices -- NUSOD 2020, J. Piprek, K. Hinzer, eds., IEEE Conference Publications Management Group, Piscataway, 2020, pp. 97--98, DOI 10.1109/NUSOD49422.2020.9217764 .
Abstract
We present a brightness- and power-scalable polarization beam combining scheme for high-power, broad-area semiconductor lasers. To achieve the beam combining, we employ Lyot-filtered optical reinjection from an external cavity, which forces lasing of the individual diodes on interleaved frequency combs with overlapping envelopes and enables a high optical coupling efficiency. We demonstrate how repeatedly introduced new stages of the external cavity allow efficient coupling of 2 n emitters. We simulate the operation of two-four-eight-sixteen coupled emitters, analyze beam coupling efficiency, and discuss possible limiting factors of this coupling scheme.

C. Brée, V. Raab, D. Gailevičius, V. Purlys, J. Montiel, G.G. Werner, K. Staliunas, A. Rathsfeld, U. Bandelow, M. Radziunas, Genetically optimized photonic crystal for spatial filtering of reinjection into broad-area diode lasers, in: 2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, OSA Technical Digest, IEEE, Piscataway, 2019, pp. 1--1, DOI 10.1109/CLEO-EQEC.2019.8871622 .
Abstract
Modern high-power broad-area semiconductor laser diodes (BASLDs) deliver optical output powers of several ten Watts at high electro-optical conversion efficiencies, which makes them highly relevant for numerous industrial, medical and scientific applications. However, lateral multimode behavior in BASLDs due to thermal lensing turns out highly detrimental, as it results in poor focusability and decreased laser beam brightnesss. Approaches to overcome this issue include improved epitaxial layer design, the optimization of evanescent spatial filtering by tailoring the emitter geometry and facet reflectivity, or Fourier spatially filtered reinjection from an external resonator [1].

C. Brée, V. Raab, J. Montiel, G.G. Werner, K. Staliunas, U. Bandelow, M. Radziunas, Lyot spectral filter for polarization beam combining of high-power, broad-area diode lasers: Modeling, simulations, and experiments, in: 2019 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, OSA Technical Digest, IEEE, Piscataway, 2019, pp. 1--1, DOI 10.1109/CLEOE-EQEC.2019.8871911 .
Abstract
Summary form only given. Recent improvements in design and development have significantly increased the relevance of high-power, broad-area laser diodes and laser diode bars in the market for industrial, high-brightness materials processing applications, like welding, soldering and cutting. Here, we present, experimentally [1] and, for the first time, in direct simulations [2], a polarization beam combining scheme, which maintains the linear polarization of the individual sources, and, unlike common wavelength multiplexing schemes, is insensitive to spectral drifts caused by variations of temperature or injection current. In our setup, two laser diodes are operated with optical reinjection from a common external cavity containing a Lyot spectral filter; cf. the setup shown in Fig. 1a). Our time-domain direct numerical simulations take into account both, the lateral, and longitudinal dimensions of the laser emitters [3]. The optical reinjection from the common external resonator was modeled by suitable Fresnel integrals in the paraxial regime, accounting for the different phase- and group retardations of ordinary and extraordinary beam components within the birefringent crystal (calcite) [4]. Using a half-wave plate for polarization rotating the emission of diode 2, the spectrally filtered feedback enforces lasing of both diodes on interleaved frequency combs. The spectrum of each diode is then localized in the respective transmission window of the Lyot filter, determined by cos 2 ??nL/? (diode 1) and sin 2 ??nL/? (diode 2), where ?? is the phase birefringence of the crystal. In consequence, both beams can be combined with maintained linear polarization and high optical coupling efficiency. Simulated and experimental results for two coupled laser diodes are shown in Figs. 1b) and c). Indeed, simulations and experiments show that the usable output power in the combined beam is 86% (simulations) and 80% (experiment).

A. Pimenov, A.G. Vladimirov, S. Amiranashvili, Analysis of temporal dissipative solitons in a delayed model of a ring semiconductor laser, in: Extended Abstracts Spring 2018, A. Korobeinikov, M. Caubergh, T. Lázaro, J. Sardanyés, eds., 11 of Trends in Mathematics, Birkhäuser, Cham, 2019, pp. 7--12, DOI 10.1007/978-3-030-25261-8_2 .
Abstract
Temporal dissipative solitons are short pulses observed in periodic time traces of the electric field envelope in active and passive optical cavities. They sit on a stable background, so that their trajectory comes close to a stable steady state solution between the pulses. A common approach to predict and study these solitons theoretically is based on the use of Ginzburg?Landau-type partial differential equations, which, however, cannot adequately describe the dynamics of many realistic laser systems. Here, for the first time, we demonstrate the formation of temporal dissipative soliton solutions in a time-delay model of a ring semiconductor cavity with coherent optical injection, operating in anomalous dispersion regime, and perform bifurcation analysis of these solutions.

S. Slepneva, U. Gowda, A. Pimenov, A.G. Vladimirov, E. Viktorov, G. Huyet, Complex dynamics of long cavity lasers, in: 2019 21st International Conference on Transparent Optical Networks (ICTON), Angers, France, M. Jaworski, M. Marciniak, eds., IEEE, Piscataway, 2019, pp. 1--4, DOI 10.1109/ICTON.2019.8839990 .
Abstract
In this paper, we will discuss the properties of long cavity frequency sweeping lasers and demonstrate various scenarios of coherence deterioration in such lasers. The long cavity lasers are known to demonstrate rich variety of dynamical regimes including formation of localised structures and transition to turbulence. The interest to frequency sweeping long cavity lasers has also recently increased due to their application for imaging and sensing. For these applications, the stability of the laser is an important parameter as it directly influences its coherence and therefore, for example, the quality of the obtained images. We investigated static, quasi static and synchronisation regimes of such lasers and analysed possible instabilities in such system. Experimentally, we considered different laser configurations which has allowed us to study the influence of the cavity length, frequency sweeping speed and the detuning. Numerically, we used a model based on a system of delayed differential equations. The numerical simulation of our model showed excellent agreement with the experimental data. In particularly, we studied the formation of dark pulses, both periodic and non-periodic, and showed that they are closely connected to Nozaki-Bekki holes previously predicted in the complex Ginzburg-Landau equation.

U. Gowda, S. Slepneva, A. Pimenov, A.G. Vladimirov, E. Viktorov, G. Huyet, Stable and unstable Nozaki--Bekki holes in a long laser, in: Proc. SPIE 10912, B. Witzigmann, M. Osiński, Y. Arakawa, eds., Physics and Simulation of Optoelectronic Devices XXVII, SPIE Digital Library, Bellingham, 2019, pp. 109120M/1--109120M/6, DOI 10.1117/12.2510300 .
Abstract
Long cavity fibre-based wavelength sweeping lasers are promising devices with a wide range of potential applications ranging from communications to life sciences. For example, Fourier Domain Mode-Locked (FDML) lasers, which are commonly used for Optical Coherence Tomography (OCT) imaging applications are long cavity lasers incorporating an intra-cavity resonator driven in resonance with the cavity round trip time. The coherence properties of such swept sources are of major importance as they define the image quality. The purpose of this work is to analyze the mechanism that deteriorates the coherence of long lasers. In our experiment, the laser included a 100nm wide semiconductor optical amplifier at 1310nm and a fibre cavity that could vary from 20m to 20km. the laser emission wavelength was controlled using a fibre based intra-cavity filter with a bandwidth of 10GHz. Near the lasing threshold and/or for fast carrier decay rate, we observed the appearance of periodic power dropouts with stable Nozaki-Bekki holes (NBH) that circulate in the laser cavity. As a function of the injection current, the laser could operate in various regimes including bi-stability between NBH and stable (cw) operation, unstable NBH or chaotic operation. Such behavior indicates that the interplay between the injection current and carrier decay rate can lead to highly coherent emission of a long cavity laser.

J.-P. Köster, M. Radziunas, A. Zeghuzi, H. Wenzel, A. Knigge, Traveling wave model based simulation of tunable multi-wavelength diode laser systems, in: Proceedings of the 19th International Conference on Numerical Simulation of Optoelectronic Devices -- NUSOD 2019, J. Piprek, K. Hinzer, eds., IEEE Conference Publications Management Group, Piscataway, 2019, pp. 75--76.
Abstract
We show simulation results of a compact, inte-grated and tunable multi-wavelength diode laser emitting around785 nm. The presented design was optimized using passivewaveguide simulations and then further analyzed by performingactive laser simulations. The latter enables deducing criticaldesign parameters not accessible via an all-passive simulation.

A. Pimenov, S. Amiranashvili, A.G. Vladimirov, Analysis of temporal dissipative solitons in a delayed model of a ring semiconductor laser, in: Extended Abstracts Spring 2018, A. Korobeinikov, M. Caubergh, T. Lázaro, J. Sardanyés, eds., 11 of Trends in Mathematics, Birkhäuser, Cham, 2019, pp. 7--12, DOI 10.1007/978-3-030-25261-8_2 .
Abstract
Temporal cavity solitons are short pulses observed in periodic time traces of the electric field envelope in active and passive optical cavities. They sit on a stable background so that their trajectory comes close to a stable CW solution between the pulses. A common approach to predict a nd study these solitons theoretically is based on the use of Ginzburg-Landau-type partial differential equations, which, however, cannot adequately describe the dynamics of many realistic laser systems. Here for the first time we demonstrate formation of temporal cavity soliton solutions in a time-delay model of a ring semiconductor cavity with coherent optical injection, operating in anomalous dispersion regime, and perform bifurcation analysis of these solutions.

A.V. Kovalev, E.A. Viktorov, N. Rebrova, A.G. Vladimirov, G. Huyet, Theoretical study of mode-locked lasers with nonlinear loop mirrors, in: Proc. SPIE 10682, Semiconductor Lasers and Laser Dynamics VIII, K. Panayotov, M. Sciamanna, R. Michalzik, eds., SPIE Digital Library, 2018, pp. 1068226/1--1068226/6.

V.Z. Tronciu, H. Wenzel, M. Radziunas, M. Reggentin, J. Wiedmann, A. Knigge, Numerical and experimental studies of a distributed Bragg reflector laser, in: Proceeding of the 6th International Conference ``Telecommunications, Electronics and Informatics'', Chisinău, Moldova, May 24--27, 2018, S. Andronic, ed., Technical University of Moldova, 2018, pp. 105--108.
Abstract
We report in this paper theoretical and experimental results on the dynamical properties of a distributed Bragg reflector (DBR) semiconductor lasers. Using the traveling wave equation model, we show that a proper choice of coupling coefficient and front facet reflectivity allows an optimization of the laser operation, such that for a wide range of currents injected into the active region the laser emits a continuous-wave beam. The numerical results are in a qualitative agreement with measured characteristics.

A. Zeghuzi, M. Radziunas, H. Wenzel, H.-J. Wünsche, U. Bandelow, A. Knigge, Modeling of current spreading in high-power broad-area lasers and its impact on the lateral far field divergence, in: Proc. SPIE 10526, Physics and Simulation of Optoelectronic Devices XXVI, B. Witzigmann, M. Osiński, Y. Arakawa, eds., SPIE Digital Library, 2018, pp. 105261H/1--105261H/10, DOI 10.1117/12.2289803 .
Abstract
The effect of current spreading on the lateral far-field divergence of high-power broad-area lasers is investigated with a time-dependent model using different descriptions for the injection of carriers into the active region. Most simulation tools simply assume a spatially constant injection current density below the contact stripe and a vanishing current density beside. Within the drift-diffusion approach, however, the injected current density is obtained from the gradient of the quasi-Fermi potential of the holes, which solves a Laplace equation in the p-doped region if recombination is neglected. We compare an approximate solution of the Laplace equation with the exact solution and show that for the exact solution the highest far-field divergence is obtained. We conclude that an advanced modeling of the profiles of the injection current densities is necessary for a correct description of far-field blooming in broad-area lasers.

M. Radziunas, U. Bandelow, C. Brée, V. Raab, H. Wenzel, A. Zeghuzi, Modeling and simulation of high-power broad-area semiconductor lasers with optical feedback from different external cavities, in: 2018 IEEE International Semiconductor Laser Conference (ISLC 2018), Santa Fe, New Mexico, USA, 16--19 September 2018, Institute of Electrical and Electronics Engineers, Inc. (IEEE), 2018, pp. SuA4/1--SuA4/2.

M. Radziunas, J. Fuhrmann, A. Zeghuzi, H.-J. Wünsche, Th. Koprucki, H. Wenzel, U. Bandelow, Efficient coupling of heat flow and electro-optical models for simulation of dynamics in high-power broad-area semiconductor devices, in: Proceedings of the 18th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2018), J. Piprek, A.B. Djurisic, eds., IEEE Conference Publications Management Group, Piscataway, NJ, 2018, pp. 91--92.

M. Kantner, U. Bandelow, Th. Koprucki, H.-J. Wünsche, Simulation of quantum dot devices by coupling of quantum master equations and semi-classical transport theory, in: Proceedings of the 17th International Conference on Numerical Simulation of Optoelectronic Devices -- NUSOD 2017, J. Piprek, M. Willatzen, eds., IEEE Conference Publications Management Group, Piscataway, 2017, pp. 217--218.

A. Zeghuzi, M. Radziunas, A. Klehr, H.-J. Wünsche, H. Wenzel, A. Knigge, Influence of nonlinear effects on the characteristics of pulsed high-power BA DBR Lasers, in: Proceedings of the 17th International Conference on Numerical Simulation of Optoelectronic Devices -- NUSOD 2017, J. Piprek, M. Willatzen, eds., IEEE Conference Publications Management Group, Piscataway, 2017, pp. 233--234.

M. Radziunas, A. Zeghuzi, J. Fuhrmann, Th. Koprucki, H.-J. Wünsche, H. Wenzel, U. Bandelow, Efficient coupling of inhomogeneous current spreading and electro-optical models for simulation of dynamics in broad-area semiconductor lasers, in: Proceedings of the 17th International Conference on Numerical Simulation of Optoelectronic Devices -- NUSOD 2017, J. Piprek, M. Willatzen, eds., IEEE Conference Publications Management Group, Piscataway, 2017, pp. 231--232.

M. Kantner, U. Bandelow, Th. Koprucki, H.-J. Wünsche, Modeling and simulation of injection dynamics for quantum dot based single-photon sources, in: Proceedings of the 16th International Conference on Numerical Simulation of Optoelectronic Devices, J. Piprek, Ch. Poulton, M. Steel, M. DE Sterke, eds., IEEE Conference Publications Management Group, Piscataway, 2016, pp. 219--220.
Abstract
Single semiconductor quantum dots embedded in p-i-n diodes have been demonstrated to operate as electrically driven single-photon sources. By means of numerical simulations one can explore the limitations in the carrier injection dynamics and further improve the device technology. We propose a comprehensive modeling approach coupling the macroscopic transport of bulk carriers with an open quantum system to describe the essential physics of such devices on multiple scales.

M. Kantner, U. Bandelow, Th. Koprucki, J.-H. Schulze, A. Strittmatter, H.-J. Wünsche, On current injection into single quantum dots through oxide-confined PN-diodes, in: Proceedings of the 16th International Conference on Numerical Simulation of Optoelectronic Devices, J. Piprek, Ch. Poulton, M. Steel, M. DE Sterke, eds., IEEE Conference Publications Management Group, Piscataway, 2016, pp. 215--216.
Abstract
Current injection into single quantum dots embedded in vertical pn-diodes featuring oxide apertures is essential to the technological realization of single-photon sources. This requires efficient electrical pumping of sub-micron sized regions under pulsed excitation to achieve control of the carrier population of the desired quantum dots. We show experimentl and theoretical evidence for a rapid lateral spreading of the carriers after passing the ocide aperture in the conventional p-i-n-design in the low-injection regime suitable for single-photon emitters. By an alternative design employing p-doping up to the oxide aperture the current spreading can be suppressed resulting in an enhanced current confinement and increased injection efficiencies.

W.W. Ahmed, S. Kumar, R. Herrero, M. Botey, M. Radziunas, K. Staliunas, Suppression of modulation instability in pump modulated flat-mirror VECSELs, in: Nonlinear Optics and its Applications IV, B.J. Eggleton, N.G.R. Broderick, A.L. Gaeta, eds., 9894 of Proceedings of SPIE, SPIE Digital Library, 2016, pp. 989406/1--989406/7.
Abstract
We show that modulation instability (MI) can be suppressed in vertical external cavity surface emitting lasers (VECSELs) by introducing a periodic spatio-temporal modulation of the pump profile which in turn allows a simple flat-mirror configuration. The stability analysis of such pump modulated flat-mirror VECSELs is performed by a modified Floquet method and results are confirmed by full numerical integration of the model equations. It is found that the amplitude of the modulation as well as its spatial and temporal frequencies are crucial parameters for high spatial beam quality emission. We identify regions of complete and partial stabilization in parameter space for VECSELs with different external cavity lengths. The proposed method is shown to efficiently stabilize VECSELs with cavity lengths ranging from millimetres up to centimetres. However, the applicability of this method becomes limited for micro-meter-long cavities due to strong intrinsic relaxation oscillations.

TH. Butler, D. Goulding, S. Slepneva, B. O'Shaughnessy, B. Kelleher, S.P. Hegarty, H.Ch. Lyu, K. Karnowski, M. Wojtkowski, A.G. Vladimirov, G. Huyet, Coherence properties of fast frequency swept lasers revealed via full electric field reconstruction, in: Physics and Simulation of Optoelectronic Devices XXIV, B. Witzigmann, M. Osiński, Y. Arakawa, eds., 9742, Proceedings of SPIE, Bellingham, Washington, 2016, pp. 97420K/1--97420K/7.
Abstract
A novel, time-resolved interferometric technique is presented allowing the reconstruction of the complex electric field output of a fast frequency swept laser in a single-shot measurement. The power of the technique is demonstrated by examining a short cavity swept source designed for optical coherence tomography applications, with a spectral bandwidth of 18 THz. This novel analysis of the complete electric field reveals the modal structure and modal evolution of the device as well as providing a time-resolved real-time characterization of the optical spectrum, linewidth and coherence properties of a dynamic rapidly swept laser.

S. Kumar, W. Ahmed, R. Herrero, M. Botey, M. Radziunas, K. Staliunas, Stabilization of broad area semiconductor amplifiers by spatially modulated potentials, in: Nonlinear Dynamics: Materials, Theory and Experiments, M. Tlidi, M. Clerc, eds., 173 of Springer Proceedings in Physics, Springer International Publishing Switzerland, Cham, 2016, pp. 139--151.
Abstract
We propose the stabilization of the output beam of Broad Area Semiconductor (BAS) amplifiers through the introduction of a spatially periodic modulated potential. We show that a periodic modulation of the pump profile in transverse and longitudinal directions, under certain ?resonance? condition, can solve two serious problems of BAS amplifiers (and possibly lasers), which are (i) the lack of an intrinsic spatial mode selection mechanism in linear amplification regimes and (ii) the modulation instability (also called Bespalov-Talanov instability) in nonlinear regimes. The elimination of these two drawbacks can significantly improve the spatial quality of the emitted beam in BAS amplifiers.

D. Turaev, A.G. Vladimirov, S. Zelik, Interaction of spatial and temporal cavity solitons in mode-locked lasers and passive cavities, in: Laser Optics (LO), 2016 International Conference, IEEE, New York, 2016, pp. 37628.
Abstract
We study interaction of well-separated localized structures of light in the presence of periodic perturbations. Oscillating localized structures were found to emit weakly decaying dispersive waves leading to a strong enhancement of the interaction and formation of new types of bound states. We discuss the applicability of our analytical results to the interpretation of experimental and numerical data reported earlier.

M. Radziunas, A multi-mode delay differential equation model for lasers with optical feedback, in: Proceedings of the 16th International Conference on Numerical Simulation of Optoelectronic Devices, J. Piprek, Ch. Poulton, M. Steel, M. DE Sterke, eds., IEEE Conference Publications Management Group, Piscataway, 2016, pp. 13--14.
Abstract
In this work, we introduce a new multi-mode (MM) delay differential equation (DDE) model suited for simulations of the Fabry-Perot type diode laser with an optical feedback from the external cavity (EC).

M. Radziunas, Modeling and simulations of edge-emitting broad-area semiconductor lasers and amplifiers, in: Parallel Processing and Applied Mathematics -- 11th International Conference, PPAM 2015 Krakow, Poland, September 6--9, 2015, Revised Selected Papers, Part II, R. Wyrzykowski, E. Deelman, J. Dongarra, K. Karczewski, J. Kitowski, K. Wiatr, eds., 9574 of Lecture Notes in Computer Science, Springer International Publishing AG Switzerland, Cham, 2016, pp. 269--276.
Abstract
A (2+1)-dimensional partial differential equation model describing spatial-lateral dynamics of edge-emitting broad-area semiconductor devices is considered. A numerical scheme based on a split-step Fourier method is implemented on a parallel computing cluster. Numerical integration of the model equations is used for optimizing of existing devices with respect to the emitted beam quality, as well as for creating and testing of novel device design concepts.

A.G. Vladimirov, A. Pimenov, S. Slepneva, G. Huyet, Distributed delay differential model of a multimode semiconductor laser, in: Lasers and Electro-Optics Europe & European Quantum Electronics Conference (Cleo/Europe-EQEC), IEEE, New York, 2017, DOI 10.1109/CLEOE-EQEC.2017.8086400 .
Abstract
A set of differential equations with distributed delay is derived for modeling of multimode ring lasers with intracavity chromatic dispersion. Analytical stability analysis of continuous wave regimes is performed and it is demonstrated that sufficiently strong anomalous dispersion can destabilize these regimes.

A.G. Vladimirov, G. Huyet, A. Pimenov, Delay differential models in multimode laser dynamics: Taking chromatic dispersion into account, in: Semiconductor Lasers and Laser Dynamics VII, 9892 of Proceedings of SPIE, SPIE, Bellingham, Washington, 2016, pp. 98920I/1--98920I/7.
Abstract
A set of differential equations with distributed delay is derived for modeling of multimode ring lasers with intracavity chromatic dispersion. Analytical stability analysis of continuous wave regimes is performed and it is demonstrated that sufficiently strong anomalous dispersion can destabilize these regimes. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

M. Kantner, U. Bandelow, Th. Koprucki, Multi-scale modeling and simulation of single-photon sources, in: Proceedings of iNOW 2015 (International Nano-Optoelectronics Workshop) (PDF only), Y. Arakawa, F. Koyama, C. Chang-Hasnain, D. Bimberg, eds., pp. 129-130.

S. Kumar, W. Ahmed, M. Radziunas, M. Botey, R. Herrero, K. Staliunas, Taming the modulation instability in semiconductor lasers, in: Transparent Optical Networks (ICTON), 2015 17th International Conference on, Budapest, M. Jaworski, M. Marciniak, eds., IEEE, New York, 2015, pp. 1--4.
Abstract
Semiconductor lasers are efficient light sources with an important drawback, the lack of an intrinsic mode selection mechanism which leads to spatio-temporal instabilities. The modulation instability that unstabilizes the homogeneous solution can be suppressed by the introduction of spatial modulations in the transverse and longitudinal directions. The present work applies this stabilization technique to two of the most popular semiconductor devices, the Broad Area Semiconductor (BAS) amplifier and the Vertical-Cavity Surface-Emitting Laser (VCSEL).

V.Z. Tronciu, M. Radziunas, H. Wenzel, Stationary states of external cavity diode laser, in: Proceedings of the 5th International Conference on Telecommunications, Electronics and Informatics (ICTEI 2015), V. Kantser, S. Andronic, eds., Technical University of Moldova, Chisinau, pp. 58--59.

M. Radziunas, R. Herrero, M. Botey, K. Staliunas, Beam shaping in spatially modulated broad area edge-emitting semiconductor lasers, in: 2015 European Conference on Lasers and Electro-Optics -- European Quantum Electronics Conference, Optical Society of America, 2015, paper CB_P_3, 2015, pp. 1--1.

M. Radziunas, V. Tronciu, E. Luvsandamdin, Ch. Kürbis, A. Wicht, H. Wenzel, Coexistence of multiple stable continuous-wave states in micro-integrated external-cavity diode lasers, in: 2015 European Conference on Lasers and Electro-Optics -- European Quantum Electronics Conference, Optical Society of America, 2015, paper CB_P_28, 2015, pp. 1--1.

M. Radziunas, Nonlinear dynamics in mode locked lasers: Modeling, simulations and analysis, in: Proceedings of the 5th International Conference on Telecommunications, Electronics and Informatics (ICTEI 2015), V. Kantser, S. Andronic, eds., Technical University of Moldova, Chisinau, 2015, pp. 94--97.

R.M. Arkhipov, M. Radziunas, A.G. Vladimirov, Theoretical analysis of the influence of external periodic forcing on nonlinear dynamics of passively mode-locked semiconductor lasers, in: Proceedings of the XIV School Seminar Wave Phenomena in Inhomogeneous Media (Waves 2014), Section 9, Nonlinear dynamics and information systems (in electronic form and in Russian), 2014, pp. 3--6.

R.M. Arkhipov, M.V. Arkhipov, Mode-locking in two section and single section lasers due to coherent interaction of light and matter in the gain and absorbing media, in: Proceedings of the XIV School Seminar Wave Phenomena in Inhomogeneous Media (Waves 2014), Section 3, Nonlinear and coherent optics (in electronic form and in Russian), 2014, pp. 43--45.

M. Kantner, Th. Koprucki, H.-J. Wünsche, Numerical simulation and optimization of electrical resistance in distributed Bragg reflectors, in: iNOW2014 -- International Nano-Optoelectronics Workshop, Luga and St. Petersburg, Russia, August 10--22, 2014, C. Chang-Hasnain, Z.I. Alferov, V.G. Dubrovskii, eds., Polytechnical University St. Petersburg, 2014, pp. 89--90.

M. Radziunas, R. Ciegis, Modeling and simulations of beam stabilization in edge-emitting broad area semiconductor devices, in: Parallel Processing and Applied Mathematics -- 10th International Conference, PPAM 2013, Warsaw, Poland, September 8--11, 2013, Revised Selected Papers, Part II, R. Wyrzykowski, J. Dongarra, K. Karczewski, J. Waśniewski, eds., LNCS 8385, Springer, Heidelberg, 2014, pp. 332--342.
Abstract
A 2+1 dimensional PDE traveling wave model describing spatial-lateral dynamics of edge-emitting broad area semiconductor devices is considered. A numerical scheme based on a split-step Fourier method is presented and implemented on a parallel compute cluster. Simulations of the model equations are used for optimizing of existing devices with respect to the emitted beam quality, as well as for creating and testing of novel device design concepts.

M. Radziunas, R. Herrero, M. Botey, K. Staliunas, Simulations and analysis of beam quality improvement in spatially modulated broad area edge-emitting devices, in: Proc. SPIE 9134, Semiconductor Lasers and Laser Dynamics VI, Brussels, Belgium, April 14, 2014, K. Panajatov, M. Sciamanna, A. Valle, R. Michalzik, eds., 2014, pp. 91340Q/1--91340Q/8.
Abstract
We simulate and analyze how beam quality improves while being amplified in edge emitting broad area semiconductor amplifiers with a periodic structuring of the electrical contacts, in both longitudinal and lateral directions. A spatio-temporal traveling wave model is used for simulations of the dynamics and nonlinear interactions of the optical fields, induced polarizations and carrier density. In the case of small beam amplification, the optical field can be expanded into few Bloch modes, so that the system is described by a set of ODEs for the evolution of the mode amplitudes. The analysis of such model provides a deep understanding of the impact of the different parameters on amplification and on spatial (angular) filtering of the beam. It is shown that under realistic parameters the twodimensional modulation of the current can lead not only to a significant reduction of the emission divergence, but also to an additional amplification of the emitted field.

R. Herrero, S. Kumar, M. Radziunas, M. Botey, K. Staliunas, Improving beam quality in broad area semiconductor amplifiers (in electronic form), in: Transparent Optical Networks (ICTON), 2014 16th International Conference on, IEEE Conference Publications, Institute of Electrical and Electronics Engineers, 2014, pp. 45--47.

V.Z. Tronciu, M. Radziunas, E. Luvsandamdin, Ch. Kürbis, A. Wicht, H. Wenzel, Simulations and experiments of external cavity diode lasers, in: 7th International Conference on Materials Science and Condensed Matters Physics. Abstracts. Chisinau, Moldova, September 16--19, 2014, 2014, pp. p. 47.

A. Glitzky, A. Mielke, L. Recke, M. Wolfrum, S. Yanchuk, D2 -- Mathematics for optoelectronic devices, in: MATHEON -- Mathematics for Key Technologies, M. Grötschel, D. Hömberg, J. Sprekels, V. Mehrmann ET AL., eds., 1 of EMS Series in Industrial and Applied Mathematics, European Mathematical Society Publishing House, Zurich, 2014, pp. 243--256.

U. Bandelow, Th. Koprucki, H.-J. Wünsche, Dynamics of classical optical fields in semiconductor lasers, in: iNOW2014 -- International Nano-Optoelectronics Workshop, Luga and St. Petersburg, Russia, August 10--22, 2014, C. Chang-Hasnain, Z.I. Alferov, V.G. Dubrovskii, eds., Polytechnical University St. Petersburg, 2014, pp. 14--15.

M. Radziunas, V.Z. Tronciu, E. Luvsandamdin, C. Kürbis, A. Wicht, H. Wenzel, Investigations of external cavity diode lasers: Simulations, analysis and experiments, in: Proceedings of the 14th International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD 2014, 1--4 September 2014, J. Piprek, J. Javaloyes, eds., IEEE Conference Publications Management Group, Piscataway, NJ, USA, 2014, pp. 149--150.

M. Radziunas, Longitudinal mode analysis of multisection ring and edge-emitting semiconductor lasers, in: Proceedings of the 14th International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD 2014, 1--4 September 2014, J. Piprek, J. Javaloyes, eds., IEEE Conference Publications Management Group, Piscataway, NJ, USA, 2014, pp. 133--134.

M. Radziunas, Simulations and analysis of beam shaping in spatially modulated broad area edge-emitting devices, in: Proceedings of 24th IEEE International Semiconductor Laser Conference (ISLC 2014), Palma de Mallorca, Spain, Sept. 7--10, 2014, 2014, pp. 19--20.

S. Amiranashvili, U. Bandelow, N. Akhmediev, Ultrashort optical solitons in nonlinear media with arbitrary dispersion, in: Proceedings of the 13th International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD 2013, 19--22 August 2013, J. Piprek, L. Chrostowski, eds., IEEE Conference Publications Management Group, Piscataway, NJ, USA, 2013, pp. 117--118.

R.M. Arkhipov, M. Radziunas, A.G. Vladimirov, Numerical simulations of the influence of injection of biharmonic radiation on the regime of passive mode-locking in semiconductor laser, in: Proceedings of the XIVth All-Russian Scientific School-Seminar ``Physics and Microwave Application'' (Waves-2013), Moscow, May 20--26, 2013, Section 5: Nonlinear Dynamics and Information Systems (electronic, in Russian), 2013, pp. 9--12.

R.M. Arkhipov, A. Pimenov, M. Radziunas, A.G. Vladimirov, Theoretical analysis of hybrid and dual mode injected semiconductor mode-locked lasers, in: Proceedings of the 2013 International Nano-Optoelectronics Workshop (iNOW2013), Cargèse, France, August 18--30, 2013, pp. B3--B4.

M. Radziunas, R. Herrero, M. Botey, K. Staliunas, Theoretical study of beam quality improvement in spatially modulated broad area edge-emitting devices, in: CLEO/Europe -- IQEC 2013 Conference Digest, OSA Technical Digest (CD) (Optical Society of America, 2013), paper CB-P.38 MON, 2013, pp. 1--1.

M. Radziunas, Traveling wave modelling and mode analysis of semiconductor ring lasers, in: CLEO/Europe -- IQEC 2013 Conference Digest, OSA Technical Digest (CD) (Optical Society of America, 2013), paper CB-P.37 MON, 2013, pp. 1--1.

B. Slepneva, B. O'Shaughnessy, S. Kelleher, A. Hegarty, A.G. Vladimirov, G. Huyet, Dynamics of Fourier domain mode locked lasers, in: Proceedings of CLEO: Applications and Technology, San Jose, California, United States, June 9--14, 2013, paper JW2A.87, Optical Society of America, 2013.

M.V. Arkhipov, R.M. Arkhipov, S.N. Bagaev, V.S. Egorov, I.A. Chekhonin, M.A. Chekhonin, Ultrafast laser beam scanning by resonant light-induced spacial periodic structures, in: Proceedings of the XIVth All-Russian Scientific School-Seminar ``Physics and Microwave Application'' (Waves-2013), Moscow, May 20--26, 2013, Section 6: Coherent and Nonlinear Optics (electronic, in Russian), 2013, pp. 6--9.

R. Herrero, M. Botey, M. Radziunas, K. Staliunas, Beam shaping in spatially modulated broad area semiconductor amplifiers, in: CLEO/Europe -- IQEC 2013 Conference Digest, OSA Technical Digest (CD) (Optical Society of America, 2013), paper IG-2.4 WED, 2013, pp. 1--1.

U. Bandelow, Th. Koprucki, K. Gärtner, A. Wilms, A. Mielke, Comprehensive mathematical modeling and simulation of semiconductor lasers, in: Proceedings of the 2013 International Nano-Optoelectronics Workshop (iNOW2013), Cargèse, France, August 18--30, 2013, pp. A7--A8.

U. Bandelow, N. Akhmediv, Solitons on a background, rogue waves, and classical soliton solutions of the Sasa--Satsuma equation, in: Laser Dynamics and Nonlinear Photonics, 2013 Sixth ``Rio De La Plata'' Workshop on, C. Masoller, I. Brener, eds., IEEE, 2013, pp. 1--2.

A. Pimenov, G. Kozyreff, V.Z. Tronciu, A.G. Vladimirov, Theoretical analysis of a multi-stripe laser array with external off-axis feedback, in: Semiconductor Lasers and Laser Dynamics V, K. Panajotov, M. Sciamanna, A. Valle, R. Michalzik, eds., 8432 of Proceedings of SPIE, SPIE, Bellingham, Washington, 2012, pp. 843212/1--843212/10.

M. Radziunas, K. Staliunas, Spatial ``rocking'' for improving the spatial quality of the beam of broad area semiconductor lasers, in: Semiconductor Lasers and Laser Dynamics V, K. Panajotov, M. Sciamanna, A.A. Valle, R. Michalzik, eds., 8432 of Proceedings of SPIE, SPIE, Bellingham, Washington, 2012, pp. 84320Q/1--84320Q/9.

E. Averlant, M. Tlidi, A.G. Vladimirov, H. Thienpont, K. Panajotov, Delay induces motion of multipeak localized structures in cavity semiconductors, in: Semiconductor Lasers and Laser Dynamics V, K. Panajotov, M. Sciamanna, A. Valle, R. Michalzik, eds., 8432 of Proceedings of SPIE, SPIE, Bellingham, Washington, 2012, pp. 84321D/1--84321D/6.

C. Brée, S. Amiranashvili, U. Bandelow, Spatio-temporal pulse propagation in nonlinear dispersive optical media, in: Proceedings of the 12th International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD'12, J. Piprek, W. Lu, eds., IEEE Conference Publications Management Group, New Jersey, USA, 2012, pp. 131--132.

A.G. Vladimirov, D. Rachinskii, M. Wolfrum, Modeling of passively mode-locked semiconductor lasers, in: Nonlinear Laser Dynamics: From Quantum Dots to Cryptography, K. Lüdge, ed., Reviews in Nonlinear Dynamics and Complexity, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2012, pp. 183--216.

M. Radziunas, A.G. Vladimirov, E.A. Viktorov, G. Fiol, H. Schmeckebier, D. Bimberg, Strong asymmetry of mode-locking pulses in quantum-dot semiconductor lasers, in: CLEO/Europe and EQEC 2011 Conference Digest, OSA Technical Digest (CD) (Optical Society of America, 2011), paper CB3_5, pp. 1--1.

M. Radziunas, K. Staliunas, Spatial ``rocking'' in broad emission area semiconductor lasers, in: CLEO/Europe and EQEC 2011 Conference Digest, OSA Technical Digest (CD) (Optical Society of America, 2011), paper CB5_2, pp. 1--1.

A. Rusu, C. Pirtac, S. Rusu, V.Z. Tronciu, On/Off phase shift keying encryption method of semiconductor lasers with an air gap (in Romanian), in: Proceeding of the 7th International Conference on Microelectronics and Computer Science, Chisinau, September 22--24, 2011, Moldova, V. Kanter, I. Balmus, eds., 1, Technical University of Moldova, 2011, pp. 402-403.

A. Rusu, C. Pirtac, S. Rusu, V.Z. Tronciu, Verification of Steiner's theorem with physical pendulum --- Computer assisted laboratory work (in Romanian), in: Proceeding of the 7th International Conference on Microelectronics and Computer Science, Chisinau, September 22--24, 2011, Moldova, V. Kanter, I. Balmus, eds., 1, Technical University of Moldova, 2011, pp. 404-405.

C. Brée, A. Demircan, G. Steinmeyer, Saturation of the all-optical Kerr effect, in: CLEO/Europe and EQEC 2011 Conference Digest, OSA Technical Digest (CD) (Optical Society of America, 2011), paper EF4_6, pp. 1-1.

V.Z. Tronciu, S.S. Rusu, A.S. Rusu, On/Off phase shift keying encryption method of semiconductor lasers with an air gap, in: Proceeding of the 7th International Conference on Microelectronics and Computer Science, Chisinau, September 22--24, 2011, Moldova, V. Kanter, I. Balmus, eds., 1, Technical University of Moldova, 2011, pp. 29-32.

V.Z. Tronciu, On the dynamics of multimode semiconductor lasers, in: Proceeding of the 7th International Conference on Microelectronics and Computer Science, Chisinau, September 22--24, 2011, Moldova, V. Kanter, I. Balmus, eds., 1, Technical University of Moldova, 2011, pp. 27--28.

M. Radziunas, A.G. Vladimirov, E.A. Viktorov, Traveling wave modeling, simulation and analysis of quantum-dot mode-locked semiconductor lasers, in: Semiconductor Lasers and Laser Dynamics IV, K. Panajotov, M. Sciamanna, A.A. Valle, R. Michalzik, eds., 7720 of Proceedings of SPIE, SPIE, 2010, pp. 77200X/1--77200X/8.

V.Z. Tronciu, C. Fiebig, M. Lichtner, H. Wenzel, Numerical and experimental investigations of DBR tapered lasers, in: Proceedings of the 3rd International Conference on Telecommunications, Electronics and Informatics (ICTEI 2010), V. Kantser, S. Andronic, eds., 1, Technical University of Moldova, Chisinau, 2010, pp. 73--76.

V.Z. Tronciu, S.S. Rusu, C. Pîrtac, Dynamics of coupled semiconductor lasers. On/off phase shift keying encryption method, in: Proceedings of the 3rd International Conference on Telecommunications, Electronics and Informatics (ICTEI 2010), V. Kantser, S. Andronic, eds., 1, Technical University of Moldova, Chisinau, 2010, pp. 77--80.

V.Z. Tronciu, Semiconductor laser a key element for new generation optoelectronic systems, in: Proceedings of the 3rd International Conference on Telecommunications, Electronics and Informatics (ICTEI 2010), V. Kantser, S. Andronic, eds., 1, Technical University of Moldova, Chisinau, 2010, pp. 67--72.

I.V. Ermakov, G. Van DER Sande, L. Gelens, A. Scire, P. Colet, C.R. Mirasso, V.Z. Tronciu, J. Danckaert, Numerical investigation of nonlinear dynamics of semiconductor ring lasers with two external cavities, in: Proceedings of the Young Optical Scientists Conference, YOSC-2009, V. Karassik, ed., Bauman Moscow State Technical University Press, 2010, pp. 106--109.

A. Jechow, D. Skoczowsky, M. Lichtner, M. Radziunas, R. Menzel, High-brightness emission from stripe-array broad area diode lasers operated in off-axis external cavities, in: High-Power Diode Laser Technology and Applications VIII, M.S. Zediker, ed., 7583 of Proceedings of SPIE, SPIE, 2010, pp. 758312/1--758312/11.

A.G. Vladimirov, M. Wolfrum, G. Fiol, D. Arsenijević, D. Bimberg, E. Viktorov, P. Mandel, D. Rachinskii, Locking characteristics of a 40-GHz hybrid mode-locked monolithic quantum dot laser, in: Semiconductor Lasers and Laser Dynamics IV, K. Panajotov, M. Sciamanna, A.A. Valle, R. Michalzik, eds., 7720 of Proceedings of SPIE, SPIE, 2010, pp. 77200Y/1--77200Y/8.

M. Radziunas, A.G. Vladimirov, E. Viktorov, Traveling wave modeling of mode-locked quantum dot semiconductor lasers, in: CLEO/Europe and EQEC 2009 Conference Digest (Optical Society of America, 2009), oral presentation CB4.4 TUE, 2009, pp. 1--1.

M. Radziunas, Simulation of switching between stable unidirectional states in semiconductor ring lasers, in: CLEO/Europe and EQEC 2009 Conference Digest (Optical Society of America, 2009), poster CB.P.12 TUE, 2009, pp. 1--1.

V.Z. Tronciu, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, Calculation of improved features of distributed-feedback tapered master-oscillator power-amplifiers, in: CLEO/Europe and EQEC 2009 Conference Digest (Optical Society of America, 2009), poster CB.P.30 TUE, 2009, pp. 1--1.

V.Z. Tronciu, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, Dynamics and stability improvement of DFB tapered master-oscillator power-amplifiers, in: Proceedings of the 6th International Conference on Microelectronics and Computer Science, Chisinau, Moldova, October 1--3, 2009, I.M. Tiginyanu, I. Balmus, eds., Technical University of Moldova, Chisinau, 2009, pp. 15-18.

V.Z. Tronciu, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, Improving the stability of distributed-feedback tapered master-oscillator power-amplifiers, in: Proceedings of the 9th International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD'09, J. Piprek, Y.-T. Lee, eds., IEEE/LEOS, 2009, pp. 55-56.

M. Schulz-Ruhtenberg, I. Babushkin, N.A. Loiko, K.F. Huang, T. Ackemann, Analysis of polarization states of broad-area vertical-cavity surface-emitting lasers below and above threshold, in: 2009 IEEE/LEOS Winter Topicals Meeting Series (WTM 2009), IEEE, 2009, pp. 178-179.

E.V. Viktorov, P. Mandel, A.G. Vladimirov, M. Wolfrum, G. Fiol, M. Kuntz, D. Bimberg, Hybrid mode-locking in a 40 GHz monolithic quantum dot laser, in: CLEO/Europe and EQEC 2009 Conference Digest (Optical Society of America, 2009), oral presentation CB4.2 TUE, 2009, pp. 1--1.

M. Radziunas, Travelling wave modeling of semiconductor ring lasers, in: Semiconductor Lasers and Laser Dynamics III, K.P. Panajotov, M. Sciamanna, A.A. Valle, R. Michalzik, eds., 6997 of Proceedings of SPIE, SPIE, 2008, pp. 69971B/1--69971B/9.

M. Lichtner, M. Radziunas, U. Bandelow, M. Spreemann, H. Wenzel, Dynamic simulation of high brightness semiconductor lasers, in: Proceedings of the 8th International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD'08, J. Piprek, E. Larkins, eds., IEEE/LEOS, 2008, pp. 65--66.

M. Radziunas, U. Troppenz, J. Kreissl, Tailoring single-mode DFB laser with integrated passive feedback section for direct modulation applications, in: Proceedings of the European Conference on Lasers and Electro-Optics, 2007, and the International Quantum Electronics Conference. CLEO/IQEC 2007 (oral presentation CB-35-WED), IEEE, 2007, pp. 1--1.

J. Kreissl, U. Troppenz, W. Rehbein, T. Gärtner, P. Harde, M. Radziunas, 40 Gbit/s directly modulated passive feedback laser with complex-coupled DFB section, in: Proceedings of ECOC 2007, VDE Verlag GmbH, Berlin/Offenbach, 2007, pp. 213--214.

T. Perez, C. Mirasso, H.-J. Wünsche, F. Henneberger, M. Radziunas, I. Fischer, Synchronization of chaotic unidirectionally coupled multisection lasers, in: Proceedings of the European Conference on Lasers and Electro-Optics, 2007, and the International Quantum Electronics Conference. CLEO/IQEC 2007 (oral presentation JSI3-2-THU), IEEE, 2007, pp. 1-1.

L. Recke, M. Wolfrum, S. Yanchuk, Dynamics of coupled semiconductor lasers, in: Analysis and Control of Complex Nonlinear Processes in Physics, Chemistry and Biology, Chapter 6, L. Schimansky-Geier, B. Fiedler, J. Kurths, E. Schöll, eds., World Scientific, New Jersey [et al.], 2007, pp. 185--212.

O.V. Ushakov, H.-J. Wünsche, F. Henneberger, M. Radziunas, Excitability of chaotic transients in a semiconductor laser, in: Proceedings of the European Conference on Lasers and Electro-Optics, 2007, and the International Quantum Electronics Conference. CLEO/IQEC 2007 (oral presentation IG6-2-THU), IEEE, 2007, pp. 1--1.

E.A. Viktorov, P. Mandel, M. Kuntz, G. Fiol, D. Bimberg, A.G. Vladimirov, M. Wolfrum, Stability of the modelocking regime in quantum dot laser, in: Proceedings of the European Conference on Lasers and Electro-Optics, 2007, and the International Quantum Electronics Conference. CLEO/IQEC 2007 (oral presentation IG6-3-THU), IEEE, 2007, pp. 1--1.

M. Radziunas, H.-J. Wünsche, B. Krauskopf, M. Wolfrum, External cavity modes in Lang--Kobayashi and traveling wave models, in: Semiconductor Lasers and Laser Dynamics II, D. Lenstra, M. Pessa, I.H. White, eds., 6184 of Proceedings of SPIE, 2006, pp. 61840X/1--61840X/9.

T. Perez, M. Radziunas, H.-J. Wünsche, C.R. Mirasso, F. Henneberger, Chaos synchronization of unidirectionally coupled multisection lasers, in: Proceedings of the 32nd European Conference on Optical Communication (ECOC 2006), 2006, pp. paper Tu3.1.5/1--Tu3.1.5/2.

U. Troppenz, J. Kreissl, W. Rehbein, C. Bornholdt, T. Gaertner, M. Radziunas, A. Glitzky, U. Bandelow, M. Wolfrum, 40 Gb/s directly modulated InGaAsP passive feedback DFB laser, in: Proceedings of the 32nd European Conference on Optical Communication (ECOC 2006), Postdeadline session, 2006, pp. Th4.5.5/1--Th4.5.5/2.

M. Radziunas, U. Bandelow, M. Wolfrum, A. Glitzky, R. Hünlich, U. Troppenz, J. Kreissl, Design of multisection semiconductor laser for 40 Gb/s direct modulation, in: Proceedings of the 31st European Conference on Optical Communication ECOC 2005, Glasgow, UK, September 25--29, 2005, 3, Institution of Electrical Engineers, London, 2005, pp. 677-678.

M. Radziunas, Tailoring the dynamics of multisection lasers for 40 Gb/s direct modulation, in: Proceedings of the 5th International Conference on ``Numerical Simulation of Optoelectronic Devices'' (NUSOD'05) in Berlin, September 19--22, 2005, H.-J. Wünsche, J. Piprek, U. Bandelow, H. Wenzel, eds., IEEE, Piscataway, NJ, 2005, pp. 29--30.

U. Troppenz, M. Hamacher, M. Radziunas, H. Heidrich, Optical switching of clockwise/anti-clockwise lasing in bus coupled microrings, in: Indium Phosphide and Related Materials, I. Thayne, J. Marsh, C. Bryce, eds., IEEE, Piscataway, 2005, IEEE Catalogue no. 05CH37633C.

M. Wolfrum, S. Yanchuk, Synchronous and asynchronous instabilities of two lasers with a long delayed coupling, in: Proceedings of the ENOC-2005 Fifth EUROMECH Nonlinear Dynamics Conference, Eindhoven, The Netherlands, August 7--12, 2005, D.H. VAN Campen, M.D. Lazurko, W.P.J.M. caps">caps">van der Oever, eds., 2005, pp. 2069--2073.

S. Yanchuk, K.R. Schneider, L. Recke, Dynamics of two F2F coupled lasers: Instantaneous coupling limit, in: Proceeding of SPIE: Semiconductor Lasers and Laser Dynamics Conference ``Photonics Europe'', 5452, SPIE, Washington, USA, 2004, pp. 51--62.

N. Korneyev, M. Radziunas, H.-J. Wünsche, F. Henneberger, Mutually injecting semiconductor lasers: Simulations for short and zero delay, in: Proceedings of SPIE: Semiconductor Lasers and Laser Dynamics Conference ``Photonics Europe'', 5452, SPIE, Washington, 2004, pp. 63--70.

V. Tronciu, R.A. Abram, M. Yamada, Dynamics of blue InGaN laser. Self pulsation and excitability, The International Conference ``40 years of TUM'', Chisinau, Moldova, 2004, pp. 112--113.

N. Korneyev, M. Radziunas, H.-J. Wünsche, F. Henneberger, Bifurcations of a DFB laser with short optical feedback: Numerical experiment, in: Physics and Simulation of Optoelectronic Devices XI, M. Osinski, H. Amano, P. Blood, eds., 4986 of SPIE Proceedings Series, Bellingham, USA, 2003, pp. 480--489.

J. Sieber, L. Recke, K.R. Schneider, Dynamics of multisection semiconductor lasers (in Russian), Proceedings of the International Conference on Differential and Functional Differential Equations, Moscow, Russian Federation, August 11 - 17, 2002, 2 of Sovrem. Probl. Mat. Fund. Naprav., 2003, pp. 70--82.

U. Bandelow, H. Gajewski, R. Hünlich, Thermodynamic designed energy model, in: Proceedings of the IEEE/LEOS 3rd International Conference on Numerical Simulation of Semiconductor Optoelectronic Devices (NUSOD'03), J. Piprek, ed., 2003, pp. 35--37.

H.-Chr. Kaiser, U. Bandelow, Th. Koprucki, J. Rehberg, Modelling and simulation of strained quantum wells in semiconductor lasers, in: Mathematics --- Key Technology for the Future. Joint Projects Between Universities and Industry, W. Jäger, H.-J. Krebs, eds., Springer, Berlin [u.a.], 2003, pp. 377--390.

M. Radziunas, H.J. Wünsche, Dynamics of multisection DFB semiconductor laser: Traveling wave and mode approximation models, in: Physics and Simulation of Optoelectronic Devices X, P. Blood, M. Osinski, Y. Arakawa, eds., 4646 of Proceedings of SPIE, Bellingham, USA, 2002, pp. 27--37.

M. Radziunas, H.J. Wünsche, LDSL: A tool for simulation and analysis of longitudinal dynamics in multisection semiconductor lasers, in: Proceedings of the Conference on Numerical Simulation of Semiconductor Optoelectronic Devices, NUSOD-02, Zürich, Switzerland, September 25--27, 2002, A. Tarraf, J. Daleiden, F. Römer, C. Prott ET AL., eds., 2002, pp. 26--27.

M. Radziunas, H.-J. Wünsche, O. Brox, F. Henneberger, Excitability of a DFB laser with short external cavity, in: Physics and Simulation of Optoelectronic Devices X, P. Blood, M. Osinski, Y. Arakawa, eds., 4646 of Proceedings of SPIE, Bellingham, USA, 2002, pp. 420--428.

U. Bandelow, M. Radziunas, V. Tronciu, H.-J. Wünsche, F. Henneberger, Tailoring the dynamics of diode lasers by passive dispersive reflectors, in: Physics and Simulation of Optoelectronic Devices VIII, R.H. Binder, P. Blood, M. Osinski, eds., 3944 of Proceedings of SPIE, SPIE, Bellingham, WA, 2000, pp. 536--545.

M. Radziunas, D.M. Kane, Traveling wave mode analysis of coherence collapse regime semiconductor laser with optical feedback, Preprint no. 3117, WIAS, Berlin, 2024, DOI 10.20347/WIAS.PREPRINT.3117 .
Abstract, PDF (11 MByte)
A highly developed traveling wave model for a semiconductor laser system supports sophisticated mode analysis of the coherence collapse regime in semiconductor lasers with delayed optical feedback. The concept of instantaneous optical modes is used. Time-frequency representations of chaotic trajectories are constructed and interpreted from synthesizing the calculated optical modes with their corresponding steady states, analysis of the mode driving and coupling sources, and field expansion into modal components. The results support detailed physical interpretation of the optical and radiofrequency spectra in the coherence collapse regime.

A.G. Vladimirov, G. Huyet, A. Pimenov, Effect of chromatic dispersion on multimode laser dynamics: Delay differential model, Preprint no. 2240, WIAS, Berlin, 2016, DOI 10.20347/WIAS.PREPRINT.2240 .
Abstract, PDF (1463 kByte)
A set of differential equations with distributed delay is derived for modeling of multimode ring lasers with intracavity chromatic dispersion. Analytical stability analysis of continuous wave regimes is performed and it is demonstrated that sufficiently strong anomalous dispersion can destabilize these regimes.

M. Tlidi, E. Averlant, A.G. Vladimirov, K. Panajotov, Spontaneous motion of cavity solitons induced by a delayed feedback, Preprint no. 1737, WIAS, Berlin, 2012, DOI 10.20347/WIAS.PREPRINT.1737 .
Abstract, Postscript (4013 kByte), PDF (1728 kByte)
We consider a broad area Vertical-Cavity Surface Emitting Laser (VCSEL) operating below the lasing threshold and subject to optical injection and time-delayed feedback. We derive a generalized delayed Swift-Hohenberg equation for the VCSEL system which is valid close to the nascent optical bistability. We first characterize the stationary cavity solitons by constructing their snaking bifurcation diagram and by showing clustering behavior within the pinning region of parameters. Then we show that the delayed feedback induces a spontaneous motion of two-dimensional cavity solitons in an arbitrary direction in the transverse plane. We characterize moving cavity solitons by estimating their threshold and calculating their velocity. Numerical 2D solutions of the governing semiconductor laser equations are in close agreement with those obtained from the delayed generalized Swift- Hohenberg equation.

I. Babushkin, Scar-like structures and their localization in a perfectly square optical billiard, Preprint no. 1465, WIAS, Berlin, 2009, DOI 10.20347/WIAS.PREPRINT.1465 .
Abstract, Postscript (1640 kByte), PDF (173 kByte)
We show that scar-like structures (SLS) in a wide aperture vertical cavity surface emitting laser (VCSEL) can be formed even in a perfectly square geometry due to interaction of polarization and spatial degrees of freedom of light. We show also that dissipation in the system induces an order among the cavity modes, so that SLS become preferred at lasing threshold. More generally, modes which are more localized both in coordinate and momentum space have in average lower losses.

E. Kuhn, Time-dependent simulation of photonic crystal surface emitting lasers, European Semiconductor Laser Workshop 2024, September 20 - 21, 2024, University of Kassel.

L. Mertenskötter, M. Kantner, Narrow--linewidth lasers, CLEO Conference, North Carolina, USA, May 5 - 10, 2024.

U. Bandelow, Applied mathematical research in nonlinear photonics at WIAS Berlin, Workshop on ``Nonlinear Photonics and Metasurfaces'', February 8, 2024, Australian National University, Canberra, Australia, February 8, 2024.

U. Bandelow, Applied mathematical research in photonics at WIAS Berlin, Workshop on ``Optics'', February 5, 2024, Monash University, Melbourne, Australia, February 5, 2024.

U. Bandelow, Hierarchies of integrable NLS-type equations and selected solutions, Workshop 2411b ``Nonlinear Optics: Physics, Analysis, and Numerics'', March 10 - 15, 2024, Mathematisches Forschungsinstitut Oberwolfach, March 11, 2024.

U. Bandelow, Modeling and simulation of semiconductor devices at WIAS: From lasers to quantum technologies, Workshop on ``Quantum Technology'', February 6, 2024, University of Melbourne, Melbourne, Australia, February 6, 2024.

U. Bandelow, Modeling of pulse propagation in nonlinear dispersive media at WIAS Berlin, Workshop on ``Integrability for Higher-Order Optical Pulse Propagation'' associated with the meeting of the Australian and New Zeeland Association of Mathematical Physics (ANZAMP), February 6 - 9, 2024, Katoomba, Australia, February 9, 2024.

M. Radziunas, Mode analysis in dynamical semiconductor laser models, 25th congress of the Australian Institute of Physics (AIP), Conference``Microelectronic Materials and Devices (COMMAD) 2024'', December 2 - 6, 2024, Melbourne, Australia.

M. Radziunas, Modeling, simulation, and analysis of all-semiconductor photonic crystal surface-emitting lasers, International Symposium on Semiconductor Optoelectronics and Nanotechnology (ISSON), December 8 - 11, 2024, Canberra, Australia.

L. Ermoneit, Simulation of single-electron shuttling for spin-qubit transport in a SiGe quantum bus, International Workshop on Computational Nanotechnology, June 12 - 16, 2023, Barcelona, Spain, June 12, 2023.

E. Kuhn, Simulation of the mode dynamics in broad ridge laser diodes, 23nd International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2023), September 18 - 22, 2023, Politecnico di Torino, Italy, September 19, 2023.

L. Mertenskötter, Kalman filtering of stochastic laser dynamics: Parameter and state space estimation from time-delayed measurements, International Conference on Structural Nonlinear Dynamics and Diagnosis, May 15 - 17, 2023, Marrakech, Morocco, May 17, 2023.

U. Bandelow, Laserdynamik -- mathematische Modellierung, MBI-Technikerschulung 2023, October 16, 2023, Max-Born-Institut, Wandlitz.

U. Bandelow, Modeling and simulation of semiconductor devices: From high-power lasers to quantum technologies, Winter School on III-Sb Applications: Non-Volatile Memories -- A Modelling Perspective, February 27 - March 3, 2023, Technische Universität Berlin, February 27, 2023.

U. Bandelow, Ultrashort solitons in the regime of event horizons in nonlinear optical media, Extreme Waves 2023, August 28 - September 1, 2023, Max-Planck-Institut für Physik komplexer Systeme, Dresden, August 29, 2023.

U. Bandelow, Unusual scenarios in the context of the modulation instability, Dissipative Solitons, Turbulence and Extreme Events in Nonlinear Photonics, September 6 - 8, 2023, International Solvay Institutes, Brussels, Belgium, September 7, 2023.

U. Bandelow, Unusual wave-mixing processes in the context of the modulation instability, XIX International Workshop on Instabilities and Nonequilibrium Structures -- INES 2023, December 4 - 8, 2023, Pontificia Universidad Catolica de Valparaiso, Chile, December 7, 2023.

M. Kantner, Modeling of semiconductor devices for quantum technologies: From single-photon sources to spin-qubit shuttles, CASA Colloquium (Centre for Analysis, Scientific Computing and Applications), Eindhoven University of Technology, Netherlands, April 5, 2023.

M. Kantner, Wiener filter enhanced estimation of the intrinsic laser linewidth from delayed self-heterodyne beat note measurements, 2023 Conference on Lasers and Electro-Optics/Europe-European Quantum Electronics Virtual Conferences, Munich, June 26 - 30, 2023.

M. Radziunas, Calculation of optical modes in large emission area photonic crystal surface-emitting lasers, 23nd International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2023), September 18 - 22, 2023, Politecnico di Torino, Italy, September 19, 2023.

M. Radziunas, Modeling of photonic crystal surface-emitting lasers, 26th International Conference on Mathematical Modelling and Analysis, May 30 - June 2, 2023, University of Latvia, Jurmala, Latvia, May 30, 2023.

M. Radziunas, Modeling, simulation, and analysis of dynamics in semiconductor lasers: A brief overview of the WIAS-FBH collaboration, Leibniz MMS Days 2023, April 17 - 19, 2023, Leibniz-Institut für Agrartechnik und Bioökonomie (ATB), Potsdam, April 18, 2023.

A.G. Vladimirov, Neutral delay differential equation Kerr cavity model, Dissipative Solitons, Turbulence and Extreme Events in Nonlinear Photonics, September 6 - 8, 2023, International Solvay Institutes, Brussels, Belgium, September 8, 2023.

A. Pimenov, Localized structures in a passive ring cavity with two filters under optical injection, Nonlinear Waves and Turbulence in Photonics 2022, WIAS Berlin, July 15, 2022.

L. Mertenskötter, M. Kantner, U. Bandelow, H. Wenzel, Non-Markovian noise in semiconductor lasers, MATH+ Day 2022, Technische Universität Berlin, November 18, 2022.

L. Mertenskötter, Data-Driven modeling of Non-Markovian noise in semiconductor laser, 22nd International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD), September 12 - 16, 2022, Politecnico di Torino, Italy.

M. Radziunas, Modeling and simulation of semiconductor lasers for high emission power applications, 25th International Conference Mathematical Modelling and Analysis, May 30 - June 2, 2022, Vilnius Gediminas Technical University, Druskininkai, Lithuania, June 1, 2022.

M. Radziunas, Steady states in dynamical semiconductor laser models and their analysis (online talk), 22nd International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) (Online Event), September 12 - 16, 2022, Politecnico di Torino, Italy, September 12, 2022.

L. Mertenskötter, M. Kantner, H. Wenzel , U. Bandelow, Modeling and optimization of semiconductor lasers for quantum metrology applications, MATH+ Day 2021 (Online Event), Technische Universität Berlin, November 5, 2021.

U. Bandelow, Modeling and simulation of the dynamics in semiconductor lasers (online talk), 91st Annual Meeting of the International Association of Applied Mathematics and Mechanics, MS1: ``Computational Photonics''' (Online Event), March 15 - 19, 2021, Universität Kassel, March 16, 2021.

M. Kantner, Noise in semiconductor lasers (online talk), MATH+ Spotlight Seminar (Online Event), MATH+, July 14, 2021.

M. Radziunas, Cascaded polarization-coupling of high-power broad-area semiconductor lasers (online talk), European Semiconductor Laser Workshop (ESLW) 2021 (Online Event), September 17 - 18, 2021, Télécom Paris and Institut Polytechnique de Paris, France, September 17, 2021.

M. Radziunas, Modeling, simulation, and analysis of dynamics in semiconductor lasers (online talk), Research seminar of the Institute of Computer Science (Online Event), Vilnius University, Lithuania, September 29, 2021.

A.G. Vladimirov, Short pulse solutions of time-delay laser models (online talk), Dynamics Days Europe 2021 (Online Event), Minisymposium MS34 ``Time Delayed Systems: Theory and Experiments'', August 23 - 27, 2021, Université Côte d'Azur, Nice, France, August 27, 2021.

U. Bandelow, Applied mathematical research in photonics at WIAS Berlin, Workshop ''Dynamics in Lasers, Photonics and Quantum Light sources'', Macquarie University, Sidney, Australia, February 18, 2020.

U. Bandelow, Applied mathematical research in photonics at WIAS Berlin, Workshop ''Photonics and Optoelectronics'', University of New South Wales, Sydney, Australia, February 17, 2020.

U. Bandelow, Applied mathematical research in photonics at WIAS Berlin, Workshop ''Nanoscience, Nano-technology, Fibre optics'', University of Sydney, Australia, February 17, 2020.

U. Bandelow, Applied mathematical research in photonics at WIAS Berlin, Workshop ''Optical fiber technology, glass development, nonlinear fibers, biophotonics'', University of South Australia, Adelaide, Australia, February 12, 2020.

U. Bandelow, Applied mathematical research in photonics at WIAS Berlin, Workshop ``Biomedical engineering, light-matter interactions'', Australian National University, Canberra, Australia, February 14, 2020.

U. Bandelow, Dynamics of high-power diode lasers (online talk), SPIE Photonics Europe (Online Event), April 3 - 7, 2020, April 6, 2020.

U. Bandelow, Modeling of nonlinear dynamical effects in photonics, Colloquium of the School of Mathematics and Physics, University of West Australia, Perth, Australia, February 19, 2020.

M. Kantner, Non-isothermal Scharfetter--Gummel scheme for electro-thermal transport simulation in degenerate semiconductors (online talk), Finite Volumes for Complex Applications IX (Online Event), June 15 - 19, 2020, NORCE - Norwegian Research Centre, Bergen, Norway, June 16, 2020.

M. Radziunas, Efficient modeling and simulation of dynamics in high-power broad-area semiconductor lasers, final EffiLas/HoTLas project meeting, Jenoptik Berlin, March 4, 2020.

M. Radziunas, Simulation of cascaded polarization-coupled systems of broad-area semiconductor lasers, 20th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2020), September 14 - 25, 2020, Politecnico di Torino, Italy.

C. Brée, V. Raab, D. Gailevičius, V. Purlys, J. Montiel, G.G. Werner, K. Staliunas, A. Rathsfeld, U. Bandelow, M. Radziunas, Genetically optimized photonic crystal for spatial filtering of reinjection into broad-area diode lasers, CLEO/Europe-EQEC 2019, Munich, June 23 - 27, 2019.

C. Brée, V. Raab, J. Montiel, G.G. Werner, K. Staliunas, U. Bandelow, M. Radziunas, Lyot spectral filter for polarization beam combining of high-power, broad-area diode lasers: Modeling, simulations, and experiments, CLEO/Europe-EQEC 2019, Munich, June 23 - 27, 2019.

A. Pimenov, Temporal solitons in a delayed model of a semiconductor laser, Waves Côte d'Azur, Nice, France, June 4 - 7, 2019.

U. Bandelow, Hybrid modeling and simulation of electrically driven quantum light sources, 12th Annual Meeting Photonic Devices, Zuse-Institut Berlin, February 15, 2019.

U. Bandelow, Modeling and simulation of electrically driven quantum dot based single-photon sources, Seminar NATEC II, Technical University of Denmark, Kgs. Lyngby, Denmark, June 7, 2019.

U. Bandelow, Self-consistent thermal-opto-electronic model for the dynamics in high-power semiconductor lasers, European Semiconductor Laser Workshop (ESLW), September 27 - 28, 2019, University College Cork, Ireland, September 28, 2019.

M. Radziunas, Efficient modeling and simulation of dynamics in high-power semiconductor lasers, 24th International Conference on Mathematical Modelling and Analysis (MMA2019), May 28 - 31, 2019, Tallinn University of Technology, Estonia, May 31, 2019.

M. Radziunas, Modeling of thermal effects in BALs, HoTLas project meeting, WIAS Berlin, February 20, 2019.

M. Radziunas, Modeling parameter dependence on temperature in high-power broad-area semiconductor lasers, Hotlas/Effilas project meeting, Ferdinand-Braun-Institut, Berlin, September 4, 2019.

A. Pimenov, Analysis of temporal localized structures in a delayed model of a semiconductor laser, Interdisciplinary Workshop on Multiple Scale Systems, Systems with Hysteresis and Trends in Dynamical Systems (MURPHYS-HSFS-2018), May 28 - June 1, 2018, Centre de Recerca Matemàtica, Bellaterra, Spain, July 30, 2018.

A. Pimenov, Analysis of temporal localized structures in a time delay model of a ring laser, 675. WE-Heraeus Seminar: Delayed Complex Systems 2018, Bad Honnef, July 2 - 5, 2018.

U. Bandelow, Semiconductor laser instabilities and dynamics emerging from mode degeneracy, International Workshop ''Synthetic Non-Hermitian Photonic Structures: Recent Results and Future Challenges'', August 13 - 17, 2018, Max Planck Institute for the Physics of Complex Systems, Dresden, August 14, 2018.

M. Radziunas, Efficient coupling of heat flow and electro-optical models for simulation of dynamics in high-power broad-area semiconductor devices, 18th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2018), WB2, November 5 - 9, 2018, The University of Hong Kong, China, November 7, 2018.

M. Radziunas, Impact of longitudinal-lateral periodic modulation of BALs to the quality of emitted beam, Project meeting of the BMBF-EffiLas/HotLas project, DILAS Diodenlaser GmbH, Mainz, September 25, 2018.

M. Radziunas, Intelligent solution for complex problems, Research Seminar of the Faculty of Science and Engineering, Macquarie University, Sydney, Australia, July 4, 2018.

M. Radziunas, Modeling and simulation of high-power broad area lasers with PWC filtering element within an external cavity, Eurostars HIP Lasers project meeting, Monocrom S. L., Vilanova, Spain, December 10, 2018.

M. Radziunas, Modeling and simulation of high-power broad area lasers with PhC filtering element, EUROSTARS project E!10524 HIP-Lasers meeting, May 22 - 23, 2018, Femtika, Vilnius, Lithuania, May 22, 2018.

M. Radziunas, Modeling and simulation of high-power broad-area semiconductor lasers with optical feedback from different external cavities, 26th International Semiconductor Laser Conference (ISLC 2018), September 16 - 19, 2018, IEEE Photonics Society, Santa Fe, USA, September 16, 2018.

M. Radziunas, Modeling of heat- and current spreading- effects in dynamic simulations of broad-area semiconductor lasers, HotLas project meeting, Jenoptik Diode Lab GmbH, Berlin, February 27, 2018.

M. Radziunas, Modeling, simulation, and analysis of nonlinear dynamics in semiconductor lasers, Research Seminar of the Faculty of Science and Engineering, Macquarie University, Sydney, Australia, July 24, 2018.

A.G. Vladimirov, Delay models in nonlinear laser dynamics, Dynamics Days Europe 2018, September 3 - 7, 2018, Loughborough University, UK, September 6, 2018.

A.G. Vladimirov, Time-delay modeling of short pulse generation in lasers, Annual International Conference ,,Days on Diffraction 2018'', June 4 - 8, 2018, Steklov Mathematical Institute, St. Petersburg, Russian Federation, June 6, 2018.

A.G. Vladimirov, Time-delay systems in multimode laser dynamics, 675. WE-Heraeus-Seminar ,,Delayed Complex Systems'', July 2 - 5, 2018, Physikzentrum Bad Honnef, July 4, 2018.

C. Brée, BALaser with intracavity PhC, Projekttreffen Eurostars, Monocrom S.L., Barcelona, Spain, November 6, 2017.

A. Pimenov, Time-delay models of multi-mode laser dynamics, SIAM Conference on Applications of Dynamical Systems (DS17), May 21 - 25, 2017, Society for Industrial and Applied Mathematics (SIAM), Snowbird, USA, May 24, 2017.

M. Radziunas, Modeling and simulation of external feedback in broad area lasers with BALaser, EFFILAS--HotLas project meeting, Jenoptik Diode Lab GmbH, Berlin, April 27, 2017.

S. Pickartz, Cancellation of Raman self-frequency shift for compression of optical pulses, 17th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD2017), July 24 - 28, 2017, Technical University of Denmark, Copenhagen, Denmark, July 28, 2017.

M. Radziunas, C. Brée, Modeling and simulation of high-power broad area lasers, HiP-Lasers project meeting, Raab-Photonic GmbH, Potsdam, May 30, 2017.

M. Radziunas, Efficient coupling of inhomogeneous current spreading and electro-optical models for simulation of dynamics in broad-area semiconductor lasers, 17th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD2017), July 24 - 28, 2017, Technical University of Denmark, Copenhagen, Denmark, July 28, 2017.

M. Radziunas, Implementation of inhomogeneous injection model into BALaser, BMBF Effilas/Hotlas project meeting, DILAS Diodenlaser GmbH, Mainz, February 21, 2017.

M. Radziunas, Modeling and simulation of high-power broad area lasers with PhC filtering element, EUROSTARS HiP-Laser project meeting, Monocrom, Vilanova, Barcelona, Spain, November 6, 2017.

M. Radziunas, Modeling and simulations of broad area lasers, BMBF Effilas/Hotlas project meeting, Ferdinand-Braun-Institut, Berlin, September 21, 2017.

A.G. Vladimirov, Mathematical modeling of dispersive and diffractive multimode lasers, 1st Sino-German Symposium on Fiber Photonics for Light Matter Interaction, September 17 - 21, 2017, Shanghai University, China, September 19, 2017.

A.G. Vladimirov, Mathematical modelling of multimode laser dynamics, Seminar of the Ultrafast Laser Laboratory, Institute for Quantum Optics, Leibniz University of Hannover, November 17, 2017.

M. Kantner, Modeling and simulation of injection dynamics for quantum dot based single-photon sources, 16th International Conference on Numerical Simulation of Optoelectronic Devices, July 11 - 15, 2016, University of Sydney, Sydney, Australia.

D. Peschka, Towards the optimization of on-chip germanium lasers, sc Matheon Workshop, 9th Annual Meeting ``Photonic Devices'', March 3 - 4, 2016, Zuse Institute Berlin, Berlin, March 4, 2016.

A. Pimenov, Effect of anomalous dispersion on the dynamics of FDML lasers, Nonlinear Dynamics in Semiconductor Lasers, WIAS, Berlin, June 17, 2016.

A. Pimenov, Numerical analysis of dissipative phase solitons in a delay differential equation model of a ring laser, Murphys-HSFS 2016 Workshop, Centre de Recerca Matemàtica, Barcelona, Spain, June 13, 2016.

A. Pimenov, Numerical stability analysis of dissipative phase solitons in a DDE model of a semiconductor laser, WIAS Workshop ``Dynamics of Delay Equations, Theory and Applications", WIAS, Berlin, October 14, 2016.

U. Bandelow, Nonlinear dynamical effects in photonics: Modeling, simulation and analysis, Coloquio del Instituto de Física, Pontificia Universidad Católica de Chile, Santiago, December 14, 2016.

M. Radziunas, A multi-mode delay differential equation model for lasers with optical feedback, Research Seminar, Macquarie University, Department of Physics and Astronomy, Sydney, Australia, July 15, 2016.

M. Radziunas, A multi-mode delay differential equation model for lasers with optical feedback, 16th International Conference on Numerical Simulation of Optoelectronic Devices, July 11 - 15, 2016, University of Sydney, Sydney, Australia.

M. Radziunas, Modeling and simulations of broad-area edge-emitting semiconductor devices, Kooperationsmeeting mit TRUMPF Laser GmbH, TRUMPF Laser GmbH, Schramberg, January 12, 2016.

M. Radziunas, Modeling and simulation of external feedback in broad area lasers with BALaser, HotLas project meeting, Jenoptik, Berlin, November 22, 2016.

M. Radziunas, Modeling and simulation of high-power broad area lasers, Kick-off meeting of the EUROSTARS project HIP-Lasers, Monocrom S. L., Vilanova, Barcelona, Spain, October 14, 2016.

M. Radziunas, Modeling and simulations of broad-area edge-emitting semiconductor devices, EffiLAS--HotLas Kick-off meeting, Jenoptik Diode Lab GmbH, Berlin, September 14, 2016.

M. Radziunas, Modeling, simulations, and analysis of nonlinear dynamics in edge-emitting semiconductor lasers, 1st Leibniz MMS Days, WIAS Berlin, Berlin, January 27, 2016.

A.G. Vladimirov, Delay differential equation models in multi-mode laser dynamics, SFB 910 Symposium: Dynamics of coupled systems and applications to lasers, Technische Universität Berlin, Berlin, April 22, 2016.

A.G. Vladimirov, Delay differential equation models of frequency swept laser light sources, International Conference on Structural Nonlinear Dynamics and Diagnosis (CSNDD'2016), University of Hassan II Casablanca, Marrakech, Morocco, May 24, 2016.

A.G. Vladimirov, Delay differential equations in modeling multimode laser dynamics, Dynamics of Delay Equations, Theory and Applications, WIAS, Berlin, October 14, 2016.

A.G. Vladimirov, Delay differential models in multimode laser dynamics: Taking chromatic dispersion into account, SPIE Photonics Europe 2016, Conference 9892 ``Semiconductor Lasers and Laser Dynamics'', Session 5, April 3 - 7, 2016, SPIE, Brussels, Belgium, April 5, 2016.

A.G. Vladimirov, Distributed delay differential equation models in laser dynamics, Volga Neuroscience Meeting 2016, July 24 - 30, 2016, from Saint Petersburg to Nizhny Novgorod, Russian Federation, July 28, 2016.

A.G. Vladimirov, Distributed delay model of a frequency swept laser with long fiber delay line, European Semiconductor Laser Workshop (ESLW) 2016, Technische Universität Darmstadt, Darmstadt, September 24, 2016.

A.G. Vladimirov, Interaction of spatial and temporal cavity solitons in mode-locked lasers and passive cavities, 17th International Conference ``Laser Optics 2016'', June 27 - July 1, 2016, Saint Petersburg, Russian Federation, June 29, 2016.

A.G. Vladimirov, Nonlinear dynamics of a frequency swept laser, Quantum Optics Seminar, Saint-Petersburg State University, Saint-Petersburg, Russian Federation, January 12, 2016.

D. Peschka, Mathematical modeling, analysis, and optimization of strained germanium-microbridges, sc Matheon Center Days, April 20 - 21, 2015, Technische Universität Berlin, Institut für Mathematik, Berlin, April 20, 2015.

A. Pimenov, Theoretical analysis of fast-moving transverse cavity solitons in a laser with an intracavitary saturable absorber, International Workshop: Waves, Solitons and Turbulence in Optical Systems (WASTOS15), Weierstraß-Institut für Angewandte Analysis und Stochastik, Berlin, October 14, 2015.

A. Pimenov, Theoretical analysis of pulse timing jitter in mode-locked semiconductor lasers, International Symposium ``Semiconductor Nanophotonics'', November 2 - 3, 2015, Technische Universität Berlin, November 2, 2015.

A. Pimenov, Theoretical investigation of multi-mode dynamics and mode-locking in an inhomogeneously broadened laser, European Semiconductor Laser Workshop 2015 (ESLW), September 24 - 25, 2015, Universidad Carlos III de Madrid, Madrid, Spain, September 24, 2015.

S. Yanchuk, Dynamic jittering and exponentially large number of periodic spiking solutions in oscillators with pulsatile delayed feedback, XXXV Dynamics Days Europe 2015, Minisymposium ``Delay-equations for Optoelectronic Systems'', September 7 - 10, 2015, University of Exeter, Centre for Systems, Dynamics and Control, Exeter, UK, September 7, 2015.

U. Bandelow, Applied Mathematical Research in Photonics at WIAS Berlin, Meeting TRUMPF-FBH-WIAS, Ferdinand-Braun-Institut, Berlin, November 20, 2015.

U. Bandelow, Applied mathematical research in photonics at WIAS Berlin, Innovation Days 2015, December 8 - 9, 2015, Leibniz-Gemeinschaft, Berlin, December 9, 2015.

U. Bandelow, Multi-dimensional modeling and simulation of electrically pumped semiconductor-based emitters, Blockseminar of SFB 787 School of Nanophotonics, May 11 - 13, 2015, TU Berlin, Graal-Müritz, May 12, 2015.

O. Omel'chenko, Controlling unstable chaos in systems of coupled oscillators, The 8th International Conference on Chaotic Modeling, Simulation and Applications (CHAOS2015), Minisymposium ``Emergent Dynamics and Control'', May 25 - 30, 2015, Institut Henri Poincaré, Paris, France, May 28, 2015.

M. Radziunas, R. Herrero, M. Botey, K. Staliunas, Beam shaping in spatially modulated broad area edge-emitting semiconductor lasers, CLEO/Europe-EQEC 2015 Conference, München, June 21 - 25, 2015.

M. Radziunas, V. Tronciu, E. Luvsandamdin, Ch. Kürbis, A. Wicht, H. Wenzel, Coexistence of multiple stable continuous-wave states in micro-integrated external-cavity diode lasers, CLEO/Europe-EQEC 2015 Conference, München, June 21 - 25, 2015.

M. Radziunas, Computation and analysis of longitudinal optical modes in multisection ring and edge-emitting semiconductor lasers, 20th International Conference on Mathematical Modeling and Analysis (MMA 2015), May 25 - 29, 2015, Sigulda, Latvia, May 27, 2015.

M. Radziunas, Modeling and simulations of edge-emitting broad-area semiconductor lasers and amplifiers, 11th International Conference on Parallel Processing and Applied Mathematics (PPAM 2015), September 6 - 9, 2015, Institute of Computer & Information Science, Krakow, Poland, September 8, 2015.

M. Radziunas, Nonlinear dynamics in mode locked lasers: Modeling, simulations and analysis, 5th International Conference ``Telecommunications, Electronics and Informatics'' (ICTEI 2015), May 20 - 24, 2015, Chisinau, Moldova, May 21, 2015.

A.G. Vladimirov, Application of delay differential equations to the analysis of nonlinear dynamics in mode-locked lasers, Colloquium Nonlinear Sciences, Universität Münster, Center for Nonlinear Sciences, May 19, 2015.

A.G. Vladimirov, Control of cavity solitons by time-delayed optical feedback, International Conference ``Dynamics, Bifurcations and Strange Attractors'', July 20 - 24, 2015, Nizhny Novgorod, Russian Federation, July 22, 2015.

A.G. Vladimirov, Feedback induced instabilities of cavity solitons, International Symposium on Physics and Applications of Laser Dynamics 2015, November 4 - 6, 2015, CentraleSupélec, Metz, France, November 6, 2015.

A.G. Vladimirov, Modelling of mode-locked semiconductor lasers, 24th International SAOT Workshop on Design, Modelling and Simulation of Lasers, June 17 - 20, 2015, Erlangen, June 19, 2015.

R.M. Arkhipov, M. Radziunas, A.G. Vladimirov, Theoretical analysis of the influence of external periodic forcing on nonlinear dynamics of passively mode-locked semiconductor lasers, XIV School Seminar ``Wave Phenomena In Inhomogeneous Media'' (Waves 2014), May 26 - 31, 2014, Moscow, Russian Federation, May 27, 2014.

R.M. Arkhipov, M.V. Arkhipov, Mode-locking in two section and single section lasers due to coherent interaction of light and matter in the gain and absorbing media, XIV School Seminar ``Wave Phenomena In Inhomogeneous Media'' (Waves 2014), Moscow, Russian Federation, May 26 - 31, 2014.

R.M. Arkhipov, Generation of ultra-short optical pulses in lasers due to coherent interaction of light with resonant medium in laser cavity, 17th International Conference ``School Foundations & Advances in Nonlinear Science'', September 29 - October 4, 2014, Minsk, Belarus, October 1, 2014.

R.M. Arkhipov, Modeling of mode-locked semiconductor lasers with external periodic forcing, "SPIE OPTO Symposium 2014", January 30 - February 8, 2014, San Francisco, USA, February 3, 2014.

R.M. Arkhipov, Modelling of mode-locked QD lasers, PROPHET Meeting, June, 26-27, 2014, June 25 - 28, 2014, Cork, Ireland, June 27, 2014.

R.M. Arkhipov, Pulse repetition-frequency multiplication of passively mode-locked semiconductor lasers coupling to an external passive cavity, ``SPIE Photonics Europe'', Brussels, Belgium, April 14 - 17, 2014.

R.M. Arkhipov, Theoretical analysis of coherent passive and self mode-locking in lasers, 16th International Conference ``Laser Optics'', June 30 -- July 4, 2014, St. Petersburg, Russian Federation, June 29 - July 6, 2014.

R.M. Arkhipov, Theoretical investigation of a passively mode-locked semiconductor laser with external periodic forcing, ``SPIE Photonics Europe'', Brussels, Belgium, April 14 - 17, 2014.

R.M. Arkhipov, Theoretical study of transient Chrenkov radiation from periodic resonance medium excited at the superluminal velocity, 16th International Conference "Laser Optics'', June 30 -- July 4, 2014, June 29 - July 6, 2014, St. Petersburg, Russian Federation, July 2, 2014.

R.M. Arkhipov, Transient Cherenkov radiation from an inhomogeneous resonant medium excited by an ultrashort laser pulse at superluminal velocity, "SPIE OPTO Symposium 2014", January 30 - February 8, 2014, San Francisco, USA, February 3, 2014.

M. Kantner, Th. Koprucki, H.-J. Wünsche, Numerical simulation and optimization of electrical resistance in GaAs/Al(x)Ga(1-x)As-based distributed Bragg reflectors, International Nano-Optoelecteonics Workshop (iNOW 2014), St. Petersburg, Russian Federation, August 9 - 23, 2014.

A. Pimenov, Robust homocline in a predator-prey system with hysteresis, International Multidisciplinary Workshop MURPHYS-HSFS-2014, WIAS Berlin, April 9, 2014.

A. Pimenov, The effect of noise on timing jitter in a mode-locked semiconductor laser, International Workshop "Nonlinear Dynamics in Semiconductor Lasers (NDSL14)", May 12--14, 2014, WIAS Berlin, May 12, 2014.

A. Pimenov, Theoretical analysis of dynamics of passively mode-locked semiconductor lasers with a focus on timing jitter, PhD Student Seminar, SFB 787 Halbleiter-Nanophotonik, Technische Universität Berlin, June 6, 2014.

A. Pimenov, Theoretical analysis of passively mode-locked inhomogeneously broadened lasers, 14th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2014), August 31 - September 4, 2014, Palma de Mallorca, Spain, September 3, 2014.

M. Radziunas, Computation and analysis of optical modes in multisection ring and edge-emitting semiconductor lasers, International Symposium ``Advances in Nonlinear Photonics'', September 29 - October 3, 2014, Minsk, Belarus, September 30, 2014.

M. Radziunas, Effective numerical algorithm for simulations of broad area semiconductor lasers, "International Workshop on Application of Parallel Computation in Industry and Engeneering (APCIE) in conjunction with EURO-PAR' 2014'', August 25 - 26, 2014, Porto, Portugal, August 25, 2014.

M. Radziunas, Longitudinal mode analysis of multisection ring and edge-emitting semiconductor lasers, 14th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2014), August 31 - September 5, 2014, Palma de Mallorca, Spain, September 2, 2014.

M. Radziunas, Modeling and simulations of beam quality improvement in broad area semiconductor devices, 19th International Conference Mathematical Modelling and Analysis, May 26 - 29, 2014, Druskininkai, Lithuania, May 26, 2014.

M. Radziunas, Simulation and analysis of the external cavity diode lasers with LDSL-tool, Research Seminar, Technical University of Moldova, Department of Physics, Chisinau, June 4, 2014.

M. Radziunas, Simulations and analysis of beam quality improvement in spatially modulated broad area edge-emitting semiconductor devices, Conference SPIE Photonics Europe, April 14-17, 2014, April 14 - 17, 2014, Brussels, Belgium, April 15, 2014.

M. Radziunas, Simulations and analysis of beam shaping in spatially modulated broad area edge-emitting devices, 24th International Semiconductor Laser Conference (ISLC 14), September 7 - 10, 2014, Palma de Mallorca, Spain, September 7, 2014.

U. Bandelow, Analytical rogue wave solutions in extended NLS-type equations, International Workshop ``Rogue Waves, Dissipative Solitons, Plasmonics, Supercontinuum and Special Fibres'', July 25 - 26, 2014, Barcelona, Spain, July 25, 2014.

U. Bandelow, Dynamics of Semiconductor Lasers, Autumn School on Laser Dynamics, September 24 - 28, 2014, University of Szeged, Bolyai Institute, Hungary.

U. Bandelow, Dynamics of classical optical fields in semiconductor lasers, International Nano-Optoelectronics Workshop (iNOW 2014), August 10 - 22, 2014, Luga and St. Petersburg, Russian Federation, August 11, 2014.

U. Bandelow, Solitons who do not want to be too short in duration, Konferenz ``Nonlinear Photonics'', July 27 - 31, 2014, Barcelona, Spain, July 29, 2014.

C. Brée, M. Kretschmar, T. Nagy, M. Hofmann, A. Demircan, U. Morgner, M. Kovacev, Fingerprint of self-compression in the high harmonic spectrum from a filament, High-Intensity Lasers and High-Field Phenomena (HILAS), Berlin, March 18 - 20, 2014.

C. Brée, Manipulating optical solitons with a group-velocity horizon, Vortrag und Junior Researcher im Rahmen des Rank Prize Fund Symposiums, June 16 - 19, 2014, Grasmere, UK, June 18, 2014.

A.G. Vladimirov, Application of delay differential equations in modeling of multimode lasers, The second International Conference on Structural Nonlinear Dynamics and Diagnosis (CSNDD'2014), May 19 - 21, 2014, Agadir, Morocco, May 19, 2014.

A.G. Vladimirov, Delay differential equation models of multimode laser dynamics, III Dynamics Days South America 2014, November 3 - 7, 2014, Vina del Mar, Chile, November 5, 2014.

A.G. Vladimirov, Delay differential equation models of multimode lasers, International Symposium ``Advances in Nonlinear Photonics'', September 29 - October 3, 2014, Minsk, Belarus, October 30, 2014.

A.G. Vladimirov, Interaction of optical breathers in mode-locked lasers and passive fiber cavities, Conference SPIE Photonics Europe, April 14-17, 2014, April 14 - 17, 2014, Brussels, Belgium, April 15, 2014.

A.G. Vladimirov, Modeling of multimode laser dynamics by means of delay differential equations, 14th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2014), September 1 - 4, 2014, Palma de Mallorca, Spain, September 3, 2014.

M. Wolfrum, Bifurcations and nonuniversal transitions to synchrony in the Sakaguchi--Kuramoto model, International Conference on Control of Self-organizing Nonlinear Systems, Rostock-Warnemünde, August 24 - 28, 2014.

M. Wolfrum, Chimera states: Patterns of coherence and incoherence in coupled oscillator systems, Institut Non Linéaire de Nice -- Sophia Antipolis, France, October 10, 2014.

M. Wolfrum, Delay-differential equations for semiconductor lasers, Autumn School on Laser Dynamics, September 24 - 28, 2014, University of Szeged, Bolyai Institute, Hungary.

R.M. Arkhipov, M. Radziunas, A.G. Vladimirov, Numerical simulation of passively mode-locked semiconductor lasers under dual mode optical injection regime, ICONO/LAT 2013 Conference, Russian Academy of Sciences, Moscow, June 17 - 22, 2013.

R.M. Arkhipov, Theoretical analysis of periodically forced semiconductor mode-locked lasers, 2013 International Nano-Optoelectronics Workshop (iNOW'2013), Cargèse, France, August 19 - 30, 2013.

R.M. Arkhipov, Spectral and temporal characteristics of radiation from a periodic resonant medium excited at the superluminal velocity, ICONO/LAT 2013 Conference, June 17 - 22, 2013, Russian Academy of Sciences, Moscow, June 20, 2013.

R.M. Arkhipov, Theoretical analysis of mode-locked semiconductor lasers with external periodic forcing, 4th G-RISC International Student Conference "Science and Progress 2013", September 30 - October 4, 2013, Sankt Petersburg, Russian Federation, October 2, 2013.

R.M. Arkhipov, Transient Cherenkov radiation from a periodic resonant medium excited by an ultrashort laser pulse propagating at superluminal velocity, 4th G-RISC International Student Conference "Science and Progress 2013", September 30 - October 4, 2013, Sankt Petersburg, Russian Federation, October 2, 2013.

R.M. Arkhipov, Transient Cherenkov radiation from an inhomogeneous resonant string excited at superluminal velocity, Extreme Nonlinear Optics & Solitons, Berlin, October 28 - 30, 2013.

M. Hofmann, Probing the transient optical response in femtosecond filaments, Extreme Nonlinear Optics & Solitons, Berlin, October 28 - 30, 2013.

A. Pérez-Serrano, Bifurcation diagrams of traveling wave models, International Workshop ''Modeling, Analysis and Simulation of Optical Modes in Photonic Devices'' MASOMO'13, WIAS Berlin, April 12, 2013.

A. Pérez-Serrano, Emission wavelength multistability in semiconductor ring lasers, CLEO/EUROPE -- IQEC 2013, München, May 12 - 16, 2013.

A. Pérez-Serrano, Multi-channel wavelength conversion using four-wave mixing in semiconductor ring lasers, Conference: CLEO Europe 2013, May 12 - 16, 2013, World of Photonics Congress, München, May 16, 2013.

A. Pimenov, N. Rebrova, D. Rachinksii, A.G. Vladimirov, Theoretical analysis of timing jitter in two-section passively mode-locked semiconductor lasers, CLEO/EUROPE -- IQEC 2013, München, May 12 - 13, 2013.

A. Pimenov, Effects of noise on a periodic solution of a system of nonlinear delay-differential equations in application to semiconductor lasers, Equadiff13, August 26 - 30, 2013, Charles University, Prague, Czech Republic, August 27, 2013.

A. Pimenov, Modelling permanent effects of a temporary stimulus (PETS) in predator-prey and SIR systems, Equadiff13, MS20 -- Slow-fast and Hysteretic Models of Population Dynamics, August 26 - 30, 2013, Prague, Czech Republic, August 26, 2013.

A. Pimenov, Theoretical analysis of delayed feedback control of solitons in semiconductor cavity, Extreme Nonlinear Optics & Solitons, Berlin, October 28 - 30, 2013.

M. Radziunas, Modeling and simulations of beam stabilization in edge-emitting broad-area semiconductor devices, Parallel Processing and Applied Mathematics (PPAM 2013), September 8 - 11, 2013, Warsaw, Poland, September 11, 2013.

M. Radziunas, Nonlinear dynamics in mode-locked lasers: Modeling, simulations and analysis, 2013 International Nano-Optoelectronics Workshop (iNOW'2013), August 19 - 31, 2013, Cargèse, France, August 28, 2013.

M. Radziunas, Theoretical study of beam quality improvement in spatially modulated broad area edge-emitting devices, CLEO/EUROPE -- IQEC 2013, München, May 12 - 16, 2013.

M. Radziunas, Traveling wave modeling and mode analysis of semiconductor ring lasers, CLEO/EUROPE -- IQEC 2013, München, May 12 - 16, 2013.

S. Slepneva, B. O'Shuaghnessy, B. Kelleher, S.P. Hegarty, A.G. Vladimirov, G. Huyet, Dynamics of Fourier domain mode locked lasers, CLEO/EUROPE -- IQEC 2013, München, May 11 - 17, 2013.

E. Averlant, A.G. Vladimirov, K. Panajotov, H. Tienpont, M. Tlidi, Delay feedback induces drift of multipeaks cavity solitons in VCSEL devices, CLEO/EUROPE -- IQEC 2013, München, May 11 - 17, 2013.

M. Tlidi, A.G. Vladimirov, A. Pimenov, K. Panajotov, D. Puzyrev, S.M. Yanchuk, S.M. Gurevich, Delay induced instabilities of cavity solitons in passive and active laser systems, CLEO/EUROPE -- IQEC 2013, München, May 11 - 17, 2013.

U. Bandelow, Turbulence and extreme events in non- linear optics, MATHEON Center Days (ECMATH), Technische Universität Berlin, November 5, 2013.

U. Bandelow, Dynamics of optical fields in semiconductor lasers, International Workshop ''Modeling, Analysis and Simulation of Optical Modes in Photonic Devices'' MASOMO'13, WIAS Berlin, April 10, 2013.

U. Bandelow, Modeling and simulation of semiconductor lasers for high speed applications, The Russell Berrie Nanotechnology Institute, Haifa, Israel, November 20, 2013.

U. Bandelow, Semiconductor lasers for high speed applications: Modeling and simulation, Technische Universität Wien, Institut für Photonik, Austria, June 7, 2013.

U. Bandelow, Ultrashort optical solitons in nonlinear media with arbitrary dispersion, 13th International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD 2013, August 16 - 24, 2013, Vancouver, Canada, August 22, 2013.

U. Bandelow, Ultrashort solitons and rogue waves in nonlinear dispersive optical media, Optics Seminar, Weizmann Institute, Rehovot, Israel, November 27, 2013.

U. Bandelow, Comprehensive mathematical modeling and simulation of semiconductor lasers, 2013 International Nano-Optoelectronics Workshop (iNOW'2013), August 19 - 30, 2013, Cargèse, France, August 26, 2013.

U. Bandelow, Heteroclinic connections and limiting cases in integrable NLS-type equations, International Workshop: Extreme Nonlinear Optics & Solitons, October 28 - 30, 2013, WIAS Berlin, October 30, 2013.

U. Bandelow, Solitons on a background, rogue waves, and classical soliton solutions of the Sasa--Satsuma equation, VI Rio de la Plata Workshop on Laser Dynamics and Nonlinear Photonics, December 6 - 13, 2013, Montevideo, Uruguay, December 17, 2013.

A.G. Vladimirov, Interaction of oscillating dissipative optical solitons, International Conference ``Dynamics, Bifurcations, and Strange Attractors'', July 1 - 5, 2013, Nizhny Novgorod State University, Russian Federation, July 5, 2013.

A.G. Vladimirov, Weak interaction of localized structures of light, Dynamical Systems and PDEs Seminar, July 1 - 5, 2013, University of Surrey, UK, July 5, 2013.

R. Arkhipov, M. Radziunas, A. Vladimirov, Theoretical analysis of hybrid mode-locked quantum dot semiconductor lasers, International Conference ``Laser Optics 2012'', St. Petersburg, Russian Federation, June 25 - 29, 2012.

R. Arkhipov, M.V. Arkhipov, S.A. Pulkin, Numerical simulations of lasing without population inversion in two-level optically dense medium, International Conference ``Laser Optics 2012'', St. Petersburg, Russian Federation, June 25 - 29, 2012.

R. Arkhipov, Mathematical modeling of mode-locking in semiconductor quantum dot lasers, TU Berlin, SFB 787, Doktorandenseminar, Technische Universität Berlin, February 17, 2012.

R. Arkhipov, Modelling of mode-locked quantum dot lasers, Initial Training Network PROPHET Workshop: Theory and Modelling in Photonics, April 11 - 19, 2012, Pavia, Italy, April 12, 2012.

R. Arkhipov, Numerical analysis of hybrid mode-locking in edge-emitting quantum dot semiconductor lasers, SPIE Photonics Europe Conference, Brussels, Belgium, April 16 - 19, 2012.

R. Arkhipov, Emission of the new frequencies in the resonant medium under the conditions of excitation by an object propagating at superluminal velocity, XIV All-Russian Scientific School-Seminar ``Wave Phenomena in Inhomogeneous Media'' (Waves-2012), May 21 - 28, 2012, Zvenigorod, Russian Federation, May 24, 2012.

R. Arkhipov, Hybrid mode-locking in semiconductor quantum dot lasers: Simulation, analysis and comparison with experiments, ITN PROPHET Mid-Term Review Meeting, October 9 - 11, 2012, Paris, France, October 11, 2012.

R. Arkhipov, Numerical analysis of hybrid mode-locking in semiconductor quantum dot lasers, XIV All-Russian Scientific School-Seminar ``Wave Phenomena in Inhomogeneous Media'' (Waves-2012), Zvenigorod, Russian Federation, May 21 - 26, 2012.

R. Arkhipov, Spectral and temporal characteristics of resonant medium radiation excited at the superluminal velocity, International Symposium Advances in Nonlinear Photonics, September 23 - 27, 2012, Belarusian State University, Minsk, Belarus, September 26, 2012.

R. Arkhipov, The new principle of the all-optical streak camera based on ultrafast laser beam deflection by light-induced coherent photonic crystal, International Symposium Advances in Nonlinear Photonics, September 23 - 27, 2012, Belarusian State University, Minsk, Belarus, September 25, 2012.

R. Arkhipov, Theoretical investigation of hybrid mode-locking in two-section semiconductor quantum dot lasers, International Symposium Advances in Nonlinear Photonics, September 23 - 27, 2012, Belarusian State University, Minsk, Belarus, September 24, 2012.

A. Pérez-Serrano, J. Javaloyes, S. Balle, Multiple channel wavelength conversion using a semiconductor ring laser, European Semiconductor Laser Workshop 2012, September 20 - 23, 2012, Vrije Universiteit Brussel, Brussels, Belgium, September 21, 2012.

A. Pimenov, Theoretical analysis of a multi-stripe laser array with external off-axis feedback, SPIE Photonics Europe 2012 Conference, April 16 - 19, 2012, Brussels, Belgium, April 17, 2012.

M. Radziunas, Hybrid mode-locking in semiconductor lasers: Simulations, analysis and experiments, ESLW2012 Workshop, September 21 - 22, 2012, Brussels, Belgium, September 21, 2012.

M. Radziunas, Spatial rocking for improving the spatial quality of the beam of broad area semiconductor lasers, SPIE Photonics Europe Conference, April 16 - 19, 2012, Brussels, Belgium, April 17, 2012.

M. Radziunas, Theoretical study of beam quality improvement in broad area semiconductor devices, International Symposium ``Advances in Nonlinear Photonics'', September 23 - 27, 2012, Belarusian State University, Minsk, September 24, 2012.

M. Radziunas, Theoretical study of beam quality improvment in broad area semiconductor devices, ESLW2012 Workshop, September 21 - 22, 2012, Brussels, Belgium, September 21, 2012.

U. Bandelow, Mathematical modeling and simulation of semiconductor lasers, Block Seminar of SFB 787 School of Nanophotonics, May 13 - 16, 2012, Technische Universität Berlin, Graal-Müritz, May 15, 2012.

U. Bandelow, Rogue waves in extended nonlinear Schrödinger equations: Integrable Sasa--Satsuma case, The Optical Society's (OSA) Annual Meeting Frontiers in Optics 2012, October 13 - 19, 2012, Rochester Section of the Optical Society of America, Rochester, USA, October 18, 2012.

U. Bandelow, Rogue waves in the Sasa--Satsuma equation, International Symposium ``Advances in Nonlinear Photonics'', September 24 - 28, 2012, Belarusian State University, Minsk, September 25, 2012.

U. Bandelow, Spatio-temporal pulse propagation in nonlinear dispersive optical media, 12th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD12), August 26 - September 4, 2012, Shanghai, China, August 30, 2012.

O. Omel'chenko, Nonuniversal transitions to synchrony in the Sakaguchi--Kuramoto model, Colloquium on Complex and Biological Systems, Universität Potsdam, November 26, 2012.

O. Omel'chenko, Partially synchronized patterns in systems of non-locally coupled phase oscillators, Institut für Mathematik, Kiev, Ukraine, February 6, 2012.

A.G. Vladimirov, Nonlinear dynamics in lasers, FP7 Marie Curie Initial Training Network PROPHET Workshop: Theory and Modelling in Photonics, April 11 - 13, 2012, Pavia, Italy, April 11, 2012.

A.G. Vladimirov, Theoretical modeling of mode-locked quantum dot lasers, SPIE Photonics Europe Conference, April 16 - 19, 2012, Brussels, Belgium, April 18, 2012.

M. Wolfrum, Collective and localized Turing patterns on irregular networks, Seminar Complex Nonlinear Processes in Chemistry and Biology, Fritz-Haber-Institut, Berlin, June 15, 2012.

M. Radziunas, Broadening of mode-locking pulses in quantum-dot semiconductor lasers: Simulation, analysis and experiments, International Workshop ``Nonlinear Photonis: Theory, Materials, Applications'', August 24 - 26, 2011, St. Petersburg, Russian Federation, August 24, 2011.

A.G. Vladimirov, Cavity solitons in broad area laser systems with delayed feedback, Yaroslavl Demidov State University, Russian Federation, September 6, 2011.

A.G. Vladimirov, Mobility properties of 2D cavity solitons in systems with delayed feedback, CLEO/Europe-EQEC Conference, 22-26 May 2011, München, May 26, 2011.

A.G. Vladimirov, Mode-locking in quantum well and quantum dot semiconductor lasers, Yaroslavl Demidov State University, Russian Federation, August 16, 2011.

A.G. Vladimirov, Synchronization of interacting temporal cavity oscillons, CLEO/Europe-EQEC Conference, 22-26 May 2011, München, May 26, 2011.

A. Wilms, A. Schliwa, Th. Koprucki, D. Breddermann, P. Mathé, A. Knorr, U. Bandelow, Theory of Coulomb scattering from two- and three-dimensional reservoirs to quantum dot states, 11th International Conference on Physics of Light-Matter Coupling in Nanostructures (PLMCN11), Berlin, April 6, 2011.

A. Wilms, Current state of our model for Coulomb scattering in semiconductor quantum dot lasers, Universität Bremen, Institut für theoretische Physik, Arbeitsgruppe Halbleiterphysik, February 23, 2011.

A. Wilms, Theory of Coulomb scattering in semiconductor quantum dot lasers, Mathematical Challenges of Quantum Transport in Nano-Optoelectronic Systems, February 4 - 5, 2011, WIAS, February 4, 2011.

M. Radziunas, Drittmittelaquise - Wie schreibe ich einen Drittmittelantrag ?, Weiterbildungsveranstaltung SW 014-SS 11, FU Berlin, August 17, 2011.

M. Radziunas, K. Staliunas, Spatial ``rocking'' in broad area semiconductor lasers, European Semiconductor Laser Workshop (ESLW) 2011, Lausanne, Switzerland, September 23 - 24, 2011.

M. Radziunas, Spatial "rocking" in broad emission area semiconductor lasers, CLEO/Europe-EQEC Conference, 22-26 May 2011, München, May 25, 2011.

M. Radziunas, Strong asymmetry of mode-locking pulses in quantum-dot semiconductor lasers, CLEO/Europe-EQEC Conference, 22-26 May 2011, München, May 24, 2011.

V.Z. Tronciu, M. Radziunas, S. Schwertfeger, A. Klehr, U. Bandelow, H. Wenzel, Modelling of dynamics in broad area semiconductor devices: Picosecond pulse amplification in tapered amplifiers, European Semiconductor Laser Workshop (ESLW) 2011, Lausanne, Switzerland, September 23 - 24, 2011.

A.G. Vladimirov, Delay differential equations model of a mode-locked semiconductor laser, Yaroslavl Demidov State University, Russian Federation, August 18, 2011.

A.G. Vladimirov, Delay differential equations models in laser dynamics, Yaroslavl Demidov State University, Russian Federation, August 30, 2011.

A. Wilms, About the Influence of the carrier reservoir dimensionality on Coulomb scattering in quantum dot materials, SFB 787, Graduiertenkolleg, Doktorandenseminar, Technische Universität Berlin, December 2, 2011.

C. Brée, A. Demircan, G. Steinmeyer, Saturation of the All-Optical Kerr Effect, CLEO/Europe-EQEC Conference, 22-26 May 2011, München, May 26, 2011.

V. Tronciu, High power lasers for modern technologies, NANO-2011 Cooperation and Networking of Universities and Research Institutes --- Study by Doing Research, October 6 - 9, 2011, Academy of Science, Institute of Electronic Engineering and Nanotechnologies, Kishinev, Moldova, October 8, 2011.

V. Tronciu, Picoseconds pulse amplification --- Theory and experiment, Technical University of Moldova, Department of Physics, Chisinau, April 20, 2011.

V. Tronciu, Nonlinear dynamics in semiconductor lasers --- Theory and experiments, Academy of Sciences of the Republic of Moldova, Institute of Energy, Chisinau, July 28, 2011.

M. Radziunas, Modeling, simulation and analysis of nonlinear dynamics in multisection semiconductor lasers, 15th International Conference ``Mathematical Modelling and Analysis'' (MMA2010), May 26 - 29, 2010, Druskininkai, Lithuania, May 29, 2010.

M. Radziunas, Traveling wave modeling, simulation and analysis of quantum-dot mode-locked semiconductor lasers, Conference on Semiconductor Lasers and Laser Dynamics IV within SPIE Photonics Europe 2010, April 12 - 16, 2010, Brussels, Belgium, April 14, 2010.

V.Z. Tronciu, C. Fiebig, M. Lichtner, H. Wenzel, Numerical and experimental investigations of DBR tapered lasers, The 3rd International Conference on Telecommunications, Electronics and Informatics (ICTEI 2010), May 20 - 23, 2010, Technical University of Moldova, Chisinau, Moldova, May 20, 2010.

V.Z. Tronciu, S.S. Rusu, C. Pîrtac, Dynamics of coupled semiconductor lasers. On/off phase shift keying encription method, The 3rd International Conference on Telecommunications, Electronics and Informatics (ICTEI 2010), Chisinau, Moldova, May 20 - 23, 2010.

V.Z. Tronciu, Chaos based communication using multi-section semiconductor laser, École Polytechnique Fédérale de Lausanne (EPFL-SB), Laboratory of Physics of Nanostructures, Switzerland, September 9, 2010.

V.Z. Tronciu, Nonlinear dynamics in semiconductor lasers --- Theory and experiments, Vrije Universiteit Brussel, Department of Applied Physics and Photonics, Belgium, September 16, 2010.

V.Z. Tronciu, Semiconductor laser a key element for new generation optoelectronic systems, The 3rd International Conference on Telecommunications, Electronics and Informatics (ICTEI 2010), May 20 - 23, 2010, Technical University of Moldova, Chisinau, Moldova, May 21, 2010.

A.G. Vladimirov, Introduction to mode-locking in lasers, Graduate College of the Collaborative Research Center SFB 787 ``Semiconductor Nanophotonics: Materials, Models, Devices'', May 9 - 11, 2010, Technische Universität Berlin, Institut für Festkörperphysik, Graal-Müritz, May 10, 2010.

A.G. Vladimirov, Locking characteristics of a 40 GHz hybrid mode-locked monolithic quantum dot laser, Conference on Semiconductor Lasers and Laser Dynamics IV within SPIE Photonics Europe 2010, April 12 - 16, 2010, Brussels, Belgium, April 14, 2010.

A.G. Vladimirov, Nonlinear dynamics in lasers, Technische Universität Berlin, Institut für Festkörperphysik, March 24, 2010.

U. Bandelow, Semiconductor laser instabilities and dynamics (short course), 10th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) 2010, September 6 - 9, 2010, Atlanta, USA, September 6, 2010.

U. Bandelow, Semiconductor lasers for high speed applications: Modeling and simulation, International Workshop on High Speed Semiconductor Lasers (HSSL 2010), October 7 - 8, 2010, Wroclaw University of Technology, Institute of Physics, Poland, October 7, 2010.

T. Girnyk, Multistability of twisted states in non-locally coupled Kuramoto-type models, Universität Potsdam, Institut für Physik und Astronomie, October 25, 2010.

T. Girnyk, Multistability of twisted states in non-locally coupled Kuramoto-type models, École Polytechnique Fédérale de Lausanne, Laboratory of Nonlinear Systems (EPFL-LANOS), Switzerland, November 17, 2010.

T. Girnyk, Stability of twisted states in repulsive Kuramoto models, Research Group Seminar, Freie Universität Berlin, research group ``Nonlinear Dynamics'', December 2, 2010.

M. Lichtner, Modeling and simulation of high power high brightness tapered and broad area lasers, Universität Potsdam, Mathematisch-Naturwissenschaftliche Fakultät, Institut für Physik und Astronomie, Arbeitsgruppe Photonik, Berlin, February 24, 2010.

M. Radziunas, Theoretical investigations of the pulse broadening in mode-locked quantum-dot semiconductor lasers, European Semiconductor Laser Workshop 2010, September 24 - 25, 2010, University of Pavia, Italy, September 24, 2010.

M. Wolfrum, Instabilities of laser devices, Doktorandenseminar des SFB 787 Halbleiter-Nanophotonik, Technische Universität Berlin, April 23, 2010.

M. Radziunas, LDSL-tool: a software for simulation and analysis of Longitudinal Dynamics in Semiconductor Lasers, Ferdinand-Braun-Institut für Höchstfrequenztechnik, Berlin, January 6, 2009.

M. Radziunas, Modeling, simulations and analysis of quantum-dot mode locked lasers, Minisymposium ``Nonlinear Dynamics in Quantum Dot Device'', November 9, 2009, WIAS, November 9, 2009.

M. Radziunas, Numerical bifurcation analysis for multi-section semiconductor lasers, International Workshop ``Trends in Bifurcation Analysis: Methods and Applications (TBA 2009)'', June 3 - 5, 2009, Milan, Italy, June 3, 2009.

M. Radziunas, Simulation and analysis of longitudinal dynamics in semiconductor laser devices, Tyndall National Institute, Photonics Theory Group, Cork, Ireland, June 25, 2009.

M. Radziunas, Simulation of switching between stable unidirectional states in semiconductor ring lasers, European Conference on Lasers and Electro-Optics and the XIth European Quantum Electronics Conference 2009 (CLEOtextsuperscript®/Europe -- EQEC 2009), Munich, June 14 - 19, 2009.

M. Radziunas, Traveling wave modeling and mode analysis of mode-locked quantum dot semiconductor lasers, European Semiconductor Laser Workshop 2009, September 25 - 26, 2009, Vienna University of Technology, Austria, September 26, 2009.

M. Radziunas, Traveling wave modeling of mode-locked quantum dot semiconductor lasers, European Conference on Lasers and Electro-Optics and the XIth European Quantum Electronics 2009 Conference (CLEO®/Europe-EQEC), June 15 - 19, 2009, Munich, June 16, 2009.

V.Z. Tronciu, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, M. Spreemann, Calculation of improved features of distributed-feedback tapered master-oscillator power-amplifiers, European Conference on Lasers and Electro-Optics and the XIth European Quantum Electronics Conference 2009 (CLEOtextsuperscript®/Europe -- EQEC 2009), Munich, June 14 - 19, 2009.

V.Z. Tronciu, Chaos based communication using multi-section semiconductor laser, Seminar of the DFG Collaborative Research Center (SFB) 787 ``Semiconductor Nanophotonics: Materials, Models, Devices'', Technische Universität Berlin, May 14, 2009.

V.Z. Tronciu, Dynamics and stability improvement of DFB tapered master-oscillator power-amplifiers, 6th International Conference on Microelectronics and Computer Science, October 1 - 3, 2009, Technical University of Moldova/Academy of Sciences of Moldova, Chisinau, Moldova, October 2, 2009.

V.Z. Tronciu, Dynamics of DFB tapered master-oscillator power-amplifiers. Applications, Seminar of the Laboratory of Theory of Semiconductors and Quantum Electronics, Academy of Sciences of Moldova, Institute of Applied Physics, Chisinau, October 9, 2009.

V.Z. Tronciu, Numerical simulations of DFB-MOPA and DBR tapered power-amplifiers, Photo Meeting, University of the Balearic Islands, Institute for Cross-Disciplinary Physics and Complex Systems (IFISC), Palma de Mallorca, Spain, June 26, 2009.

V.Z. Tronciu, Numerical simulations of DFB-MOPA and DBR tapered power-amplifiers, Universidad Politécnica de Madrid, Departamento de Tecnología Fotónica, Spain, June 29, 2009.

A.G. Vladimirov, Hybrid mode-locking in a 40 GHz monolithic quantum dot laser, European Conference on Lasers and Electro-Optics and the XIth European Quantum Electronics 2009 Conference (CLEO®/Europe-EQEC), June 14 - 19, 2009, Munich, June 16, 2009.

A. Wilms, E. Malic, J.-E. Kim, Th. Koprucki, A. Knorr, U. Bandelow, Microscopic model of semiconductor QD-gain, International Nano-Optoelectronic Workshop (iNOW 2009), Stockholm, Sweden, and Berlin, Germany, August 2 - 15, 2009.

A. Wilms, Gewinnspektren von Quantenpunkten, Doktorandenseminar des Graduiertenkollegs des SFB 787 "Halbleiter-Nanophotonik", Technische Universität Berlin, November 20, 2009.

U. Bandelow, 3D semiclassical multi-species modeling of QD lasers, International Nano-Optoelectronic Workshop (iNOW 2009), August 2 - 15, 2009, Royal Institute of Technology/Technical University of Berlin, Stockholm/Berlin, Sweden, August 14, 2009.

U. Bandelow, Improving the stability of distributed-feedback tapered master-oscillator power-amplifiers, 9th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) 2009, September 14 - 18, 2009, Gwangju Institute of Science and Technology (GIST), Korea (Republic of), September 15, 2009.

U. Bandelow, Semiconductor laser instabilities and dynamics (short course), 9th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) 2009, September 14 - 18, 2009, Gwangju Institute of Science and Technology (GIST), Korea (Republic of), September 16, 2009.

M. Radziunas, Numerical bifurcation analysis of a PDE model for multisection semiconductor lasers, Workshop ``Bifurcation in Dynamical Systems with Applications'', May 19 - 21, 2008, Universität Bielefeld, Fakultät für Mathematik, May 20, 2008.

M. Radziunas, Simulation of CW and CCW mode switching in semiconductor ring lasers, European Semiconductor Laser Workshop ESLW 2008, September 19 - 20, 2008, Technische Universiteit Eindhoven, Netherlands, September 19, 2008.

M. Radziunas, Traveling wave modelling of seminconductor ring lasers, SPIE Photonics Europe Conference, April 7 - 10, 2008, Strasbourg, France, April 9, 2008.

A.G. Vladimirov, Bifurcation analysis of a model of passively mode-locked quantum dot laser, SPIE Photonics Europe Conference, April 7 - 10, 2008, Strasbourg, France, April 8, 2008.

A.G. Vladimirov, Delay differential models of passively mode-locked quantum dot lasers, Laser Optics 2008, June 23 - 28, 2008, St. Petersburg, Russian Federation, June 25, 2008.

A.G. Vladimirov, Mode-locking in monolithic semiconductor lasers, University College Cork, Tyndall National Institute, Ireland, March 12, 2008.

U. Bandelow, Dynamic simulation of high brightness semiconductor lasers, 8th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) 2008, September 1 - 5, 2008, University of Nottingham, UK, September 2, 2008.

U. Bandelow, Modeling and analysis of master-oscillator power-amplifier seminconductor lasers, University of Washington, Seattle, USA, October 16, 2008.

U. Bandelow, Modellierung und Simulation von Halbleiterlasern, Graduate College of the Collaborative Research Center SFB 787 ``Semiconductor Nanophotonics: Materials, Models, Devices'', May 21 - 23, 2008, Technische Universität Berlin, Institut für Festkörperphysik, Graal-Müritz, May 23, 2008.

U. Bandelow, Quantum-classical coupling in multi quantum well lasers, 4th Workshop ``Mathematical Models for Transport in Macroscopic and Mesoscopic Systems'', February 7 - 10, 2008, WIAS, Berlin, February 8, 2008.

M. Lichtner, Modeling and parallel simulation of high power semiconductor lasers, PARA 2008: Workshop on State-of-the-Art in Scientific and Parallel Computing, Minisymposium on Applications of Parallel Computation in Industry and Engineering, May 13 - 16, 2008, Trondheim, Norway, May 14, 2008.

M. Radziunas, U. Troppenz, J. Kreissl, Tailoring single-mode DFB laser with integrated passive feedback section for direct modulation applications, European Conference on Lasers and Electro-Optics, 2007/International Quantum Electronics Conference (CLEO-IQEC 2007), Munich, June 17 - 22, 2007.

M. Radziunas, Simulation and analysis of the multimode model for semiconductor ring lasers, PHASE Conference, Metz, France, March 28 - 30, 2007.

M. Radziunas, Tailoring a passive feedback DFB laser for direct modulation applications, PHASE Conference, March 28 - 30, 2007, Metz, France, March 29, 2007.

M. Radziunas, Traveling wave modeling of semiconductor ring lasers, Workshop on Nonlinear Dynamics in Semiconductor Lasers, November 19 - 21, 2007, WIAS, Berlin, November 20, 2007.

M. Radziunas, Travelling wave modelling of the semiconductor ring lasers, European Semiconductor Lasers Workshop (ESLW 2007), September 14 - 15, 2007, Fraunhofer-Institut für Nachrichtentechnik, Heinrich-Hertz-Institut, Berlin, September 14, 2007.

S. Yanchuk, Eckhaus instability in systems with large delay, International Conference on Differential Equations (EQUADIFF 07), August 5 - 11, 2007, Vienna University of Technology, Austria, August 7, 2007.

M. Radziunas, Tailoring a passive feedback DFB laser for direct modulation applications, Heinrich-Hertz-Institut, Berlin, April 17, 2007.

U. Bandelow, 40 Gbit/s direct modulation in DFB lasers with integrated feedback, Workshop on Nonlinear Dynamics in Semiconductor Lasers, November 19 - 21, 2007, WIAS, Berlin, November 20, 2007.

U. Bandelow, Efficient modeling and analysis of dynamical effects in semiconductor laser devices, University of Nottingham, George Green Institute, UK, July 6, 2007.

U. Bandelow, Enhanced modulation bandwidth by integrated feedback, Rio de la Plata Workshop on Noise, Chaos and Complexity in Lasers and Nonlinear Optics, December 3 - 6, 2007, Punta del Este, Uruguay, December 5, 2007.

U. Bandelow, Feedback enhanced modulation bandwidth, Dynamics Days Europe, University of Loughborough, UK, July 12, 2007.

U. Bandelow, Nichtlineare Effekte in Halbleiterlasern und optischen Fasern, Habilitandenkolloquium, Humboldt-Universität zu Berlin, Institut für Physik, April 17, 2007.

U. Bandelow, Semiconductor laser instabilities and dynamics (Short Course SC 0702), 7th International Conference ``Numerical Simulation of Optoelectronic Devices'' (NUSOD'07), University of Delaware, Newark, USA, September 25, 2007.

M. Lichtner, Modeling and simulation of high power laser diodes, Workshop on Nonlinear Dynamics in Semiconductor Lasers, November 19 - 21, 2007, WIAS, Berlin, November 20, 2007.

A. Vladimirov, Numerical bifurcation analysis of a mode-locked semiconductor laser, Workshop on Nonlinear Dynamics in Semiconductor Lasers, November 19 - 21, 2007, WIAS, Berlin, November 21, 2007.

A.G. Vladimirov, Passive mode-locking in quantum dot lasers, Joint Seminar on Quantum Optics, St. Petersburg State University and Herzen State Pedagogical University, Russian Federation, December 26, 2007.

M. Radziunas, T. Köhler, ttfamily LDSL-tool: Simulation and analysis of dynamics in semiconductor lasers, Laser-Optik-Berlin, March 23 - 24, 2006.

M. Radziunas, Agreement between cavity modes in traveling wave and Lang--Kobayashi models of laser with delayed feedback, Cross-disciplinary Physics Seminar, Mediterranean Institute for Advanced Studies (IMEDEA), Palma de Mallorca, Spain, May 9, 2006.

M. Radziunas, External cavity modes in Lang-Kobayashi and traveling wave models, SPIE Conference Photonic Europe 2006, April 2 - 7, 2006, Strasbourg, France, April 5, 2006.

M. Radziunas, Reduction and numerical bifurcation analysis of a PDE model for multisection lasers, 6th Crimean School and Workshops ``Nonlinear Dynamics, Chaos and Applications'', May 15 - 26, 2006, Yalta, Crimea, Ukraine, May 22, 2006.

M. Radziunas, Simulation and analysis of the Traveling Wave model for multisection semiconductor lasers with LDSL-tool, WIAS-Day, Berlin, February 24, 2006.

M. Radziunas, Stabilization of orbits in semiconductor laser with external resonator, Workshop ``Complex Dynamics and Delay Effects in Coupled Systems'', September 11 - 13, 2006, Humboldt-Universität zu Berlin, September 12, 2006.

M. Radziunas, Traveling wave modeling of mode-locking in ring lasers, Workshop ``Nonlinear Dynamics in Modelocked Lasers and Optical Fibers'', July 13 - 14, 2006, WIAS, Berlin, July 14, 2006.

M. Lichtner, M. Radziunas, L. Recke, M. Wolfrum, Nonlinear dynamical effects in integrated optoelectronic structures, Evaluation Colloquium of the DFG Research Center sc Matheon, Berlin, January 24 - 25, 2006.

U. Bandelow, Modeling and simulation of optoelectronic devices, Kick-off Workshop ``Materials in New Light'', Humboldt-Universität zu Berlin, Institut für Physik, Berlin, January 6, 2006.

U. Bandelow, Modellierung und Simulation optoelektronischer Bauelemente, Berliner Industriegespräche, Deutsche Physikalische Gesellschaft, Magnus-Haus, Berlin, September 6, 2006.

U. Bandelow, Modellierung und Simulation von Pulsquellen, Status Seminar TerabitOptics Berlin, Heinrich-Hertz-Institut für Nachrichtentechnik, Berlin, July 4, 2006.

U. Bandelow, Multi-dimensional modeling and simulation of VCSELs, Project Meeting ''SFB Nanophotonics'', Technische Universität Berlin, September 1, 2006.

U. Bandelow, Simulation and analysis of spatio-temporal effects in complex laser structures, Kick-off Workshop ``Materials in New Light'', Humboldt-Universität zu Berlin, Institut für Physik, Berlin, January 6, 2006.

A. Glitzky, R. Nürnberg, U. Bandelow, ttfamily WIAS-TeSCA: Simulation of semiconductor lasers, Laser-Optik-Berlin, March 23 - 24, 2006.

M. Lichtner, A spectral gap mapping theorem and smooth invariant center manifolds for semilinear hyperbolic systems, 6th AIMS International Conference on Dynamical Systems, Differential Equations & Applications, June 25 - 28, 2006, Université de Poitiers, France, June 28, 2006.

A. Vladimirov, Dynamics of light pulses in mode-locked lasers, 6th Crimean School and Workshops ``Nonlinear Dynamics, Chaos and Applications'', May 15 - 26, 2006, Yalta, Crimea, Ukraine, May 20, 2006.

A. Vladimirov, Nonlinear dynamics and bifurcations in multimode and spatially distributed laser systems, June 20 - 23, 2006, St. Petersburg State University, Russian Federation, June 20, 2006.

A. Vladimirov, Nonlinear dynamics in multimode and spatially extended laser systems, Moscow State University, Physics Faculty, Russian Federation, November 10, 2006.

M. Radziunas, H.-J. Wünsche, V. Tronciu, Stability of continuous wave states in semiconductor laser with external resonator, Workshop on PHysics and Applications of SEmiconductor Lasers (PHASE 2005), Supélec --- Ecole Supérieure d'Electricité, Metz, France, March 29 - 30, 2005.

M. Radziunas, H.-J. Wünsche, Traveling-wave modeling of semiconductor lasers and amplifiers, 5th International Conference ``Numerical Simulation of Optoelectronic Devices'' (NUSOD 05), September 19 - 22, 2005, Humboldt-Universität, Berlin, September 19, 2005.

M. Radziunas, U. Bandelow, M. Wolfrum, A. Glitzky, R. Hünlich, U. Troppenz, J. Kreissl, Design of multisection semiconductor laser for 40 Gb/s direct modulation, 31st European Conference on Optical Communication ECOC 2005, Glasgow, UK, September 25 - 29, 2005.

M. Radziunas, Numerical bifurcation analysis of the traveling wave model of multisection semiconductor lasers, Workshop ``Qualitative Numerical Analysis of High-dimensional Nonlinear Systems'', March 21 - 24, 2005, University of Bristol, UK, March 23, 2005.

M. Radziunas, Reduction and numerical bifurcation analysis of the PDE model of multisection semiconductor lasers, Matheon Workshop on Model Reduction, Technische Universität, Berlin, November 7, 2005.

M. Radziunas, Simulation and analysis of the Traveling Wave model for multisection semiconductor lasers, Workshop ``Nonlinear Dynamics in Photonics'', May 2 - 4, 2005, WIAS, Berlin, May 4, 2005.

M. Radziunas, Stability of continuous wave states in semiconductor laser with external resonator, Minisymposium ``Laser + Resonator'', WIAS, Berlin, February 17, 2005.

M. Radziunas, Tailoring the dynamics of multisection lasers for 40 Gb/s direct modulation, 5th International Conference ``Numerical Simulation of Optoelectronic Devices'' (NUSOD 05), September 19 - 22, 2005, Humboldt-Universität, Berlin, September 20, 2005.

M. Radziunas, Tailoring the dynamics of multisection lasers for 40 Gb/s direct modulation, Evaluation of DIMOLA-Project, Fraunhofer-Institut für Nachrichtentechnik, Heinrich-Hertz-Institut, Berlin, May 18, 2005.

M. Radziunas, Tayloring the dynamics of multisection semiconductor lasers for 40 Gbit/s direct modulation, European Semiconductor Laser Workshop (ESLW) 2005, September 23 - 24, 2005, Glasgow, UK, September 24, 2005.

A. Vladimirov, D. Turaev, D. Rachinskii, Delay differential models of mode-locking in semiconductor lasers, International Conference on Coherent and Nonlinear Optics, May 11 - 16, 2005, St. Petersburg, Russian Federation, May 14, 2005.

A. Vladimirov, 40 GHz modelocking in monolithic semiconductor lasers, WIAS-Day, Berlin, February 23, 2005.

A. Vladimirov, Theoretical analysis of dynamical instabilities in a mode-locked semiconductor laser, Workshop ``Nonlinear Dynamics in Photonics'', May 2 - 4, 2005, WIAS, Berlin, May 3, 2005.

S. Yanchuk, Appearance of patterns in delay coupled laser arrays, Universität Potsdam, January 31, 2005.

S. Yanchuk, Properties of the Lang-Kobayashi model with large delay, Workshop ``Nonlinear Dynamics in Photonics'', May 2 - 4, 2005, WIAS, Berlin, May 2, 2005.

M. Nizette, A. Vladimirov, M. Wolfrum, D. Rachinskii, Delay differential equations for passive mode-locking, International Quantum Electronics Conference, München, June 12 - 17, 2005.

U. Bandelow, Analyse dynamischer Effekte in Optoelektronik und Photonik, Institutsseminar, Ferdinand-Braun-Institut für Höchstfrequenztechnik, Berlin, December 9, 2005.

U. Bandelow, Modellierung und Simulation von Pulsquellen, Status Seminar of the Terabit-Optics-Berlin Project, Fraunhofer Institut für Nachrichtentechnik, Heinrich-Hertz-Institut, Berlin, May 31, 2005.

U. Bandelow, Reduced amplitude noise in monolithic mode-locked semiconductor lasers, Workshop on PHysics and Applications of SEmiconductor Lasers (PHASE 2005), March 29 - 30, 2005, Supélec --- Ecole Supérieure d'Electricité, Metz, France, March 30, 2005.

M. Wolfrum, Synchronous and asynchronous instabilities of two lasers with a long delayed coupling, EUROMECH Nonlinear Dynamics Conference (ENOC 2005), August 7 - 12, 2005, Eindhoven, Netherlands, August 8, 2005.

M. Radziunas, Forced locking in multimode semiconductor lasers, WIAS Workshop ``Synchronization and High-dimensional Chaos in Coupled Systems'', November 15 - 16, 2004, Berlin, November 16, 2004.

M. Radziunas, Simulation and analysis of 40 GHz monolithic mode-locked lasers, Joint International Workshop OPTIMIST, EPIC and COST288, October 17 - 20, 2004, Università ``La Sapienza'', Rome, Italy, October 20, 2004.

S. Yanchuk, Dynamics of two F2F coupled lasers: Instantaneous coupling limit, SPIE Photonics Europe 2004 Conference ``Semiconductor Lasers and Laser Dynamics'', April 27 - 30, 2004, Strasbourg, France, April 28, 2004.

S. Yanchuk, Intermittent synchronization in a system of coupled lasers, WIAS Workshop ``Synchronization and High-dimensional Chaos in Coupled Systems'', November 15 - 16, 2004, Berlin, November 15, 2004.

U. Bandelow, M. Radziunas, Time domain simulation of 40 GHz mode-locked semiconductor lasers, WIAS Mini-Symposium on Mode-locked Semiconductor Lasers, March 22 - 23, 2004, Berlin, March 22, 2004.

U. Bandelow, 40 GHz mode-locked semiconductor lasers: Theory, simulation and experiments, Annual Meeting 2004 of the Optical Society of America (OSA) ``Frontiers in Optics'', October 10 - 14, 2004, Rochester, USA, October 11, 2004.

U. Bandelow, Modeling of 40 GHz mode-locked semiconductor lasers, European Semiconductor Laser Workshop (ESLW'04), September 2 - 4, 2004, Chalmers University of Technology, Department of Microtechnology and Nanoscience, Särö, Sweden, September 4, 2004.

U. Bandelow, Modellierung und Simulation von Pulsquellen, Status Seminar of the Terabit-Optics-Berlin Project, Technische Universität Berlin, May 3, 2004.

U. Bandelow, Modellierung und Simulation von Pulsquellen, Status Seminar of the Terabit-Optics-Berlin Project, Technische Universität Berlin, November 2, 2004.

U. Bandelow, Time-domain modeling of ps-OEIC, Joint International Workshops OPTIMIST, EPIC and COST288, June 2 - 4, 2004, Athens, Greece, June 3, 2004.

A.G. Vladimirov, D. Turaev, G. Kozyrev, Delay differential equations for a passively mode-locked laser, EPS-QEOD Europhoton Conference on Solid State and Fiber Coherent Light Sources, August 29 - September 3, 2004, European Physical Society, Lausanne, Switzerland, August 31, 2004.

A.G. Vladimirov, DDE-based modelling of passively mode-locked 40 GHz semiconductor lasers, WIAS Mini-Symposium on Mode-locked Semiconductor Lasers, March 22 - 23, 2004, Berlin, March 22, 2004.

U. Bandelow, M. Radziunas, Simulation of mode-locked lasers with LDSL-tool, European Quantum Electronics Conference (EQEC 2003), June 23 - 27, 2003, München, June 26, 2003.

U. Bandelow, Modeling and simulation of mode-locked lasers, WIAS Minisymposium on Pulse Generation in Laser Diodes, Berlin, June 12, 2003.

U. Bandelow, Report on WIAS activities concerning COST Action 288, Kick-off Meeting for the Cost Action 288, COST TIST Secretariat, Brussels, Belgium, April 7, 2003.

U. Bandelow, Simulation of 40 GHz mode-locked multisection DBR lasers, European Semiconductor Laser Workshop (ESLW'03), September 19 - 20, 2003, Torino, Italy, September 20, 2003.

U. Bandelow, Simulation of mode-locked lasers based on a distributed time-domain model, WIAS Workshop ``Dynamics of Semiconductor Lasers'', September 15 - 17, 2003, Berlin, September 17, 2003.

U. Bandelow, Thermodynamic designed energy model, 3rd Topical meeting on Numerical Simulation of Semiconductor Optoelectronic Devices (NUSOD'03), October 14 - 16, 2003, University of Tokyo, Japan, October 14, 2003.

M. Radziunas, Computation of the stationary states of traveling wave laser model and their analysis, WIAS Workshop ``Multiscale Systems and Applications'', April 3 - 5, 2003, Berlin, April 5, 2003.

M. Radziunas, Dynamics of longitudinal modes in multisection semiconductor lasers, WIAS Workshop ``Dynamics of Semiconductor Lasers'', September 15 - 17, 2003, Berlin, September 15, 2003.

M. Radziunas, Forced periodic frequency locking: Application of path-following tools, WIAS Workshop ``Dynamical Systems, Synchronization, Lasers'', February 26 - 27, 2003, Berlin, February 27, 2003.

M. Radziunas, Numerical bifurcation analysis of the PDE system describing dynamics in multi-section semiconductor laser, The European Conference on Numerical Mathematics and Advanced Applications (ENUMATH 2003), August 18 - 22, 2003, Prague, Czech Republic, August 21, 2003.

S. Bauer, O. Brox, M. Biletzke, J. Kreissl, M. Radziunas, B. Sartorius, H.-J. Wünsche, Speed potential of active feedback lasers, CLEO/Europe-EQEC 2003, München, July 22 - 27, 2003.

M. Lichtner, M. Radziunas, L. Recke, J. Rehberg, K.R. Schneider, D8 -- Nichtlineare dynamische Effekte in integrierten optoelektronischen Strukturen, MathInside---Überall ist Mathematik, event of the DFG Research Center ``Mathematics for Key Technologies'' on the occasion of the Open Day of Urania, Berlin, September 13, 2003 - September 27, 2000.

K.R. Schneider, Bifurcation in mode approximation models of semiconductor lasers, Grodno State University, Faculty of Mathematics, Belarus, December 3, 2003.

K.R. Schneider, Modeling of the longitudinal dynamics of semiconductor lasers, 8th International Conference ``Mathematical Modelling and Analysis 2003'' (MMA), ECMI, May 28 - 31, 2003, Vilnius, Lithuania, May 29, 2003.

A. Vladimirov, A new DDE model for passive mode-locking, WIAS Workshop ``Dynamics of Semiconductor Lasers'', September 15 - 17, 2003, Berlin, September 17, 2003.

A.G. Vladimirov, Passive mode-locking in semiconductor lasers, Institute for Laser Physics, St. Petersburg, Russian Federation, December 25, 2003.

M. Wolfrum, Instabilities of semiconductor lasers with delayed optical feedback, Workshop ``Delay Equations and Applications'', September 8 - 11, 2003, Bristol, UK, September 10, 2003.

S. Yanchuk, Synchronization of two mutually coupled semiconductor lasers: Instantaneous coupling limit, WIAS Workshop ``Dynamics of Semiconductor Lasers'', September 15 - 17, 2003, Berlin, September 16, 2003.

S. Yanchuk, Synchronization phenomena in semiconductor laser, Sfb 555 Workshop ``Complex Nonlinear Processes'', September 11 - 13, 2003, Berlin, September 12, 2003.

S. Yanchuk, Synchronization of two coupled Lang-Kobayashi systems, National Institute of Applied Optics, Florence, Italy, May 7, 2003.

S. Yanchuk, Synchronization problem in two-section semiconductor lasers, Forschungsseminar ``Angewandte Analysis'', Humboldt-Universität zu Berlin, Institut für Mathematik, July 7, 2003.

M. Radziunas, Analysis and simulation of active feedback lasers, Minisymposium ``DFB Laser with Amplifying Feedback'', WIAS, Berlin, November 28, 2002.

M. Radziunas, Dynamics of multi-section DFB semiconductor laser: Traveling wave and mode approximation models, Physics and Simulation of Optoelectronics Devices X, January 21 - 25, 2002, San Jose, California, USA, January 21, 2002.

M. Radziunas, Excitability of a DFB laser with short external cavity, Physics and Simulation of Optoelectronics Devices X, San Jose, California, USA, January 24, 2002.

M. Radziunas, LDSL: A tool for simulation and analysis of longitudinal dynamics in multisection semiconductor lasers, International Conference on Numerical Simulation of Semiconductor Optoelectronic Devices (NUSOD-02), September 25 - 27, 2002, Eidgenössische Technische Hochschule Zürich, Switzerland, September 25, 2002.

M. Radziunas, Numerical bifurcation analysis of PDE system describing dynamics in multi-section semiconductor laser, Dynamical Methods for Differential Equations, September 4 - 7, 2002, Medina del Campo, Spain, August 6, 2002.

M. Radziunas, Simulation and analysis of dynamics in multi-section semiconductor DFB laser, First SIAM-EMS Conference ``Applied Mathematics in our Changing World'', September 3 - 6, 2001, Berlin, September 3, 2001.

M. Radziunas, Traveling wave model and its mode approximations analyzing and designing semiconductor lasers, WIAS Workshop ``Dynamics of Semiconductor Lasers'', September 13 - 15, 2001, Berlin, September 14, 2001.

H. Gajewski, U. Bandelow, H. Stephan, K.R. Schneider, M. Radziunas, M. Wolfrum, J. Sieber, F. Jochmann, L. Recke, Modellierung von Halbleiterlasern --- Strukturbildung in Raum und Zeit, Evaluation of Sfb 555 ``Complex Nonlinear Processes'', Humboldt-Universität zu Berlin, April 5, 2001 - September 27, 2000.

M. Radziunas, K.R. Schneider, Tayloring of semiconductor lasers for optical communicator networks, 3rd International Symposium "`Investigation of Nonlinear Dynamic Effects in Production Systems"', Brandenburgische Technische Universität Cottbus, September 26 - 27, 2000.

M. Radziunas, Modelling of multisection semiconductor lasers, International Colloquium "`Applications of Mathematics"', September 29 - 30, 2000, Hamburg, September 29, 2000.

H. Wenzel, E. Kuhn, P. Crump, M. Radziunas, Theory of the linewidth-power product of photonic-crystal surface-emitting lasers, Preprint no. 11246, Cornell University, 2024, DOI 10.48550/arXiv.2402.11246 .
Abstract
A general theory for the intrinsic (Lorentzian) linewidth of photonic-crystal surface-emitting lasers (PCSELs) is presented. The effect of spontaneous emission is modeled by a classical Langevin force entering the equation for the slowly varying waves. The solution of the coupled-wave equations, describing the propagation of four basic waves within the plane of the photonic crystal, is expanded in terms of the solutions of the associated spectral problem, i.e. the laser modes. Expressions are given for photon number, rate of spontaneous emission into the laser mode, Petermann factor and effective Henry factor entering the general formula for the linewidth. The theoretical framework is applied to the calculation of the linewidth-power product of air-hole and all-semiconductor PCSELs. For output powers in the Watt range, intrinsic linewidths of a few tens of Hertz are predicted if stable single mode operation is ensured.

D.M. Kane, M. Radziunas, Chaos spectrum -- Semiconductor laser with delayed optical feedback, Preprint no. arXiv.2312.14353, Cornell University, 2023, DOI 10.48550/arXiv.2312.14353 .
Abstract
Maximizing the rf bandwidth associated with the chaotic output from tailored operation of nonlinear semiconductor laser systems is an ongoing research effort. The early pioneering research was done in semiconductor laser with delayed optical feedback systems, which continue to be researched. We report numerical simulations of this system, using a travelling wave model. The results provide new insights into the impact of key device parameters affecting the chaos bandwidth and spectrum. Linewidth enhancement factor and the nonlinear gain saturation parameter are found to be the most important parameters when seeking to optimize the chaotic output. We reassess a standard definition being used to report chaos bandwidth. We propose that more spectral information should be reported if numerical and experimental research results are to be of most value into the future. A database from previous experimental study is also analyzed to connect with the predictions of the numerical simulations. This elucidates the links between the chaos bandwidth achieved in real systems and the semiconductor laser parameters. The results inform recommendations for semiconductor laser parameters that will better support broadband chaos generation in whatever semiconductor-gain-medium-based nonlinear system approach is being used. They elucidate the physics of both the envelope and the fine structure of the rf spectrum of coherence collapse.

M. Kantner, L. Mertenskötter, Accurate evaluation of self-heterodyne laser linewidth measurements using Wiener filters, Preprint no. arXiv:2301.10645, Cornell University, 2023, DOI 10.48550/arXiv.2301.10645 .
Abstract
Self-heterodyne beat note measurements are widely used for the experimental characterization of the frequency noise power spectral density (FN-PSD) and the spectral linewidth of lasers. The measured data, however, must be corrected for the transfer function of the experimental setup in a post-processing routine. The standard approach disregards the detector noise and thereby induces reconstruction artifacts, i.e., spurious spikes, in the reconstructed FN-PSD. We introduce an improved post-processing routine based on a parametric Wiener filter that is free from reconstruction artifacts, provided a good estimate of the signal-to-noise ratio is supplied. Building on this potentially exact reconstruction, we develop a new method for intrinsic laser linewidth estimation that is aimed at deliberate suppression of unphysical reconstruction artifacts. Our method yields excellent results even in the presence of strong detector noise, where the intrinsic linewidth plateau is not even visible using the standard method. The approach is demonstrated for simulated time series from a stochastic laser model including 1 / f-type noise.

S. Slepneva, B. O'Shaughnessy, A.G. Vladimirov, S. Rica, G. Huyet, Turbulent laser puffs, Preprint no. arXiv:1801.05509, Cornell University Library, 2018.
Abstract
The destabilisation of laminar flows and the development of turbulence has remained a central problem in fluid dynamics since Reynolds' studies in the 19th century. Turbulence is usually associated with complex fluid motions and most of the studies have so far been carried out using liquids or gases. Nevertheless, on a theoretical viewpoint, turbulence may also arise in a wide range of fields such as biology and optics. Here we report the results of experimental and theoretical investigation of the characteristic features of laminar-turbulent transition in a long laser commonly used as a light source in medical imaging and sensing applications. This laminar to turbulence transition in the laser light is characterized by the appearance of turbulent puffs similar to those commonly observed in pipe flows and is accompanied by a loss of coherence and limits the range of applications. We present both experimental results and numerical simulations demonstrating that this transition is mediated by the appearance of a convective instability where localised structures develop into drifting bursts of turbulence, in complete analogy with spots, swirls and other structures in hydrodynamic turbulence

M. Schulz-Ruhtenberg, I. Babushkin, N.A. Loiko, K.F. Huang, T. Ackemann, Polarization properties in the transition from below to above lasing threshold in broad-area vertical-cavity surface-emitting lasers (electronic only), Preprint no. arXiv:0909.3812, Cornell University Library, arXiv.org, 2009.
Abstract
For highly divergent emission of broad-area vertical-cavity surface-emitting lasers (VCSELs) a rotation of the polarization direction by up to 90 degrees occurs when the pump rate approaches the lasing threshold. Well below threshold the polarization is parallel to the direction of the transverse wave vector and is determined by the transmissive properties of the Bragg reflectors that form the cavity mirrors. In contrast, near-threshold and above-threshold emission is more affected by the reflective properties of the reflectors and is predominantly perpendicular to the direction of transverse wave vectors. Two qualitatively different types of polarization transition are demonstrated: an abrupt transition, where the light polarization vanishes at the point of the transition, and a smooth one, where it is significantly nonzero during the transition.

I. Babushkin, Scar-like structures and non-integrability in a perfectly square optical billiard (electronic only), Preprint no. arXiv:0909.4330, Cornell University Library, arXiv.org, 2009.
Abstract
We show that scar-like structures (SLS) in a wide aperture vertical cavity surface emitting laser (VCSEL) can be formed even in a perfectly square geometry due to interaction of polarization and spatial degrees of freedom of light. We show also that dissipation in the system induces an order among the cavity modes, so that SLS become preferred at lasing threshold. More generally, modes which are more localized both in coordinate and momentum space have in average lower losses.