Highlights
For a mathematical description of complex devices with structures from the scale of nm up to mm, one has to use efficient models on different levels of complexity.
Fig. 1: Schematics of a Fourier domain modelocked laser (a), a threesection Distributed Feedback laser (b), and a tapered MasterOscillator PowerAmplifier laser (c).
The most simple rate equation (ODE) models can recover qualitative dynamics of mutually coupled lasers or lasers with an optical injection. For simulation and analysis of conventional or Fourierdomain modelocked lasers (see Fig. 1a) and of laser systems with delayed feedback or coupling, one can use more complex delay differential equation (DDE) models. The spatiotemporal dynamical behavior of more general edgeemitting multisection semiconductor laser devices and coupled laser systems (see Fig. 1b) can be described by systems of nonlinear dissipative 1+1 dimensional hyperbolic PDEs (TravelingWave (TW) equations for the longitudinally propagating optical fields), nonlinearly coupled to systems of ODEs for carrier densities. For tapered and broad area lasers (see Fig. 1c), the lateral space dimension has to be taken into account, which leads to coupled systems of nonlinear second order PDEs in two spatial and one temporal dimensions.
As a particular feature, these models typically include effects on different scales in space and time and have discontinuous coefficients (heterostructures).
Fig. 2: Scheme of a highpower broadarea laser (a), top view (with external cavity) (b), and transverse cross section with optically active zone, AZ (c). The computational domains of model components are indicated in (b) and (c), whereas the diagram (d) illustrates the coupling of these models.
In general, when simulating spatialtemporal dynamics of highpower broadarea edgeemitting semiconductor lasers, see Figs. 2a and 2b, one has to account for inhomogeneous current spreading and heatflow induced effects. In the first approximation, these contributions can be accounted for by several specially prepared spatially distributed parameters of the TW model. For a more comprehensive study of the laser dynamics, one has to perform instantaneous or, at least, intermediatetime updates of these parameters. For calculation of these updates, the 2+1dimensional TW model is coupled to the static (quasi)threedimensional PDE models that determine the instantaneous currentspreading and the timeaveraged heatflow in the corresponding 3dimensional regions of the laser, see Figs. 2c and 2d.
Fig. 3: Coupling of 2^{n} emitters by an nstaged cascaded external cavity containing various properly located optical elements. The coupling of the first two diodes within Stage 1 is shown explicitly.
The coupled modeling approach, see Fig. 2d, allows comprehensive simulations of spatialtemporal dynamics in various highpower semiconductor lasers and a reliable study of several lasers coupled by optical feedback from a mutual simple or specially designed external cavity, see Fig. 3
Publications
Monographs

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. 153182, (Chapter Published).
Abstract
A hierarchy of 1 (time) + 1 (space) dimensional firstorder 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. 237251, (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. 121150, (Chapter Published).

U. Bandelow, H. Gajewski, R. Hünlich, Chapter 3: FabryPerot Lasers: Thermodynamicsbased Modeling, in: Optoelectronic Devices  Advanced Simulation and Analysis, J. Piprek, ed., Springer, New York, 2005, pp. 6385, (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 1922, 2005, IEEE, Piscataway, NJ, 2005, 134 pages, (Collection Published).
Articles in Refereed Journals

A. Pimenov, S. Slepneva, Nonlinear dynamical properties of frequency swept fiberbased semiconductor lasers, Journal of Physics: Photonics, 3 (2021), pp. 044002/1044002/11, DOI 10.1088/25157647/ac1324 .
Abstract
We investigate dynamics of semiconductor lasers with fiberbased unidirectional ring cavity that can be used as frequency swept sources. We identify key factors behind the reach dynamical behaviour of such lasers using stateoftheart experimental and analytical methods. Experimentally, we study the laser in static, quasistatic 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 modelocked classB lasers, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 104 (2021), pp. 014215/1014215/13, DOI 10.1103/PhysRevE.104.014215 .
Abstract
Using the multiscale technique we develop a generalized version of the classB 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 classB Haus modelocked model, our model is able to describe not only Qswitched instability of the fundamental modelocked regime, but also the appearance of harmonic modelocked regimes with the increase of the pump power. 
A. Zeghuzi, J.P. Koester, M. Radziunas, H. Christopher, H. Wenzel, A. Knigge, Spatially modulated broadarea lasers for narrow lateral farfield divergence, Optics Express, 29 (2021), pp. 2513325141, DOI 10.1364/OE.430804 .
Abstract
A novel laser design is presented that combines a longitudinallateral gainloss modulation with an additional phase tailoring achieved by etching rectangular trenches. At 100 A pulsed operation, simulations predict a farfield profile with 0.3degree full width at half maximum where a 0.4degreewide main lobe contains 40% of the emitted optical output power. While farfield measurements of these structured lasers emitting 10 ns long pulses with 35 W peak power confirm a substantial enhancement of radiation within the central onedegree angular range, the measured farfield 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. 129, 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 selfcontained 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 timedependent coupledwave 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 (Kfactor) and the effective Alphafactor including the effects of nonlinear gain (gain compression) and refractive index (Kerr effect), gain dispersion and longitudinal spatial hole burning in multisection cavity structures. The effect of linewidth narrowing due to feedback from an external cavity often described by the socalled 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 twosection distributed Bragg reflector laser. 
A.G. Vladimirov, S. Suchkov, G. Huyet, S.K. Turitsyn, Delaydifferentialequation model for modelocked lasers based on nonlinear optical and amplifying loop mirrors, Physical Review A, 104 (2021), pp. 033525/1033525/8, DOI 10.1103/PhysRevA.104.033525 .
Abstract
Delay differential equation model of a NOLMNALM modelocked 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 classB laser flip instability leading to a period doubling cascade and development of squarewave 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 modelocked 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. 47/147/18, 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 Kerrcavities 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 semiconductorbased fiber laser, and propose an approach to derive reduced delaydifferential equation models taking into account the dispersion of the intracavity fiber delay line. Using these equations we perform the stability and bifurcation analysis of injectionlocked 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. 49034906, 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 timedelayed model, we discuss the reasons for longterm sustainability of these solutions. We suggest that the observed dropouts are closely related to the coherent structures of the cubic complex GinzburgLandau equation. 
A.V. Kovalev, P.S. Dmitriev, A.G. Vladimirov, A. Pimenov, G. Huyet, E.A. Viktorov, Bifurcation structure of a sweptsource laser, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 101 (2020), pp. 012212/1012212/5, DOI 10.1103/PhysRevE.101.012212 .
Abstract
We numerically analyze a delay differential equation model of a shortcavity semiconductor laser with an intracavity frequencyswept 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 narrowband filter, there exist two bursting cycles determined by different parts of a continuouswave 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 broadridgewaveguide lasers, Semiconductor Science and Technology, 36 (2020), pp. 015014/1015014/12, DOI 10.1088/13616641/abc6e7 .
Abstract
The lateral brightness achievable with highpower GaAsbased laser diodes having long and broad waveguides is commonly regarded to be limited by the onset of higherorder lateral modes. For the study of the lateralmode 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 powercurrent 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 broadarea 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 modelocked VECSEL, Optics Letters, 45 (2020), pp. 252255, DOI 10.1364/OL.45.000252 .
Abstract
We introduce a spin?flip model for a verticalexternalcavity surfaceemitting 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 modelocked 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. MontielPonsoda, G. GarreWerner, K. Staliunas, U. Bandelow, M. Radziunas, Beamcombining scheme of highpower broadarea semiconductor lasers with Lyotfiltered reinjection: Modeling, simulations, and experiments, Journal of the Optical Society of America. B, 36 (2019), pp. 17211730, DOI 10.1364/JOSAB.36.001721 .
Abstract
A brightness and powerscalable polarization beam combining scheme for highpower, broadarea semiconductor laser diodes is investigated numerically and experimentally. To achieve the beam combining, we employ Lyotfiltered 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 broadarea laser diode arrays for costefficient material processing, which requires highbrilliance emission and optical powers in the kWregime. 
A. Pimenov, A.G. Vladimirov, Dynamics of an inhomogeneously broadened passively modelocked laser, The European Physical Journal B. Condensed Matter and Complex Systems, 92 (2019), pp. 114/1114/12, DOI 10.1140/epjb/e2019906428 .
Abstract
We study theoretically the effect of inhomogeneous broadening of the gain and absorption lines on the dynamics of a passively modelocked laser. We demonstrate numerically using travelling wave equations the formation of a Lambdip instability and suppression of Qswitching in a laser with large inhomogeneous broadening. We derive simplified delaydifferential equation model for a modelocked 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. 21332155, 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 oneway 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 angledfacet laser diode chips, Applied Physics B: Lasers and Optics, 66 (2019), pp. 125/1125/12, DOI 10.1007/s003400197178z .
Abstract
We present and compare theoretical and experimental results on the electrooptical performance of extended cavity diode lasers (ECDLs) that employ two ridge waveguide designs for the singletransverse 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 intracavity 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 intracavity facet is antireflection coated and features a residual intensity reflectivity of the order 10?4. The second design employs a bent ridge waveguide intersecting the antireflectioncoated intracavity 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 electrooptical 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 nonthermal farfield blooming in highpower broadarea lasers, IEEE J. Quantum Electron., 55 (2019), pp. 2000207/12000201/7, DOI 10.1109/JQE.2019.2893352 .
Abstract
With rising current the lateral farfield angle of highpower broadarea lasers widens (farfield blooming) which can be partly attributed to nonthermal effects due to carrier induced refractive index and gain changes that become the dominant mechanism under pulsed operation. To analyze the nonthermal contribution to farfield 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 preassumptions regarding the modal composition of the field is made and filamentation is automatically accounted for, the highly dynamic timedependent 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 dualwavelength diode laser system, Optical and Quantum Electronics, 51 (2019), pp. 334/1334/12, DOI 10.1007/s1108201920502 .
Abstract
We present our design of a compact, integrated and tunable dualwavelength 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 travelingwave 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 allpassive simulation. 
A. Zeghuzi, H.J. Wünsche, H. Wenzel, M. Radziunas, J. Fuhrmann, A. Klehr, U. Bandelow, A. Knigge, Timedependent simulation of thermal lensing in highpower broadarea semiconductor lasers, IEEE J. Select. Topics Quantum Electron., 25 (2019), pp. 1502310/11502310/10, 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 selfheating within broadarea lasers. Although the temperature increase is small under pulsed operation, a waveguide that is formed within a fewnslong pulse can result in a transition from a gainguided to an indexguided structure, leading to near and far field narrowing. Under continuous wave operation the longitudinally varying temperature profile is obtained selfconsistently. 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. 42074210, 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 electrooptical and heattransport models for highpower broadarea semiconductor lasers, Optical and Quantum Electronics, 51 (2019), pp. 69/169/10, DOI 10.1007/s1108201917921 .
Abstract
In this work, we discuss the modeling of edgeemitting highpower broadarea semiconductor lasers. We demonstrate an efficient iterative coupling of a slow heat transport (HT) model defined on multiple verticallateral laser crosssections with a fast dynamic electrooptical (EO) model determined on the longitudinallateral domain that is a projection of the device to the active region of the laser. Whereas the HTsolver calculates temperature and thermallyinduced refractive index changes, the EOsolver exploits these distributions and provides timeaveraged field intensities, quasiFermi potentials, and carrier densities. All these timeaveraged distributions are used repetitively by the HTsolver 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 classA nonlinear mirror modelocked laser, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 100 (2019), pp. 012216/1012216/7, DOI 10.1103/PhysRevE.100.012216 .
Abstract
Using a simple delay differential equation model we study theoretically the dynamics of a unidirectional classA 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 Turingtype instabilities, as well as by a bifurcation leading to the appearance of squarewaves. We investigate the formation of squarewaves and modelocked pulses in the system. We show that modelocked 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 modelocked 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 broadarea laser, Journal of Optics, 20 (2018), pp. 095804/1095804/7, DOI 10.1088/20408986/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 lowerorder 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 timedelay model of a wideaperture modelocked semiconductor laser, Philosophical Transactions of the Royal Society A : Mathematical, Physical & Engineering Sciences, 376 (2018), pp. 20170372/120170372/14, DOI 10.1098/rsta.2017.0372 .
Abstract
Recently, a mechanism of formation of light bullets (LBs) in wideaperture 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 Haustype model equation. In this paper we relax the MF approximation and study LB formation in a model of a wideaperture three section laser with a long diffractive section and short absorber and gain sections. To this end we derive a nonlocal delaydifferential 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 roundtrip are not small perturbations anymore. 
M. Khoder, M. Radziunas, V. Tronciu, G. Verschaffelt, Study of wavelength switching time in tunable semiconductor microring lasers: Experiment and travelling wave description, OSA Continuum, 1 (2018), pp. 12261240, 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 counterclockwise 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 redemitting distributed Bragg reflector lasers by means of numerical simulations, IET Optoelectronics, 12 (2018), pp. 228232, DOI 10.1049/ietopt.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 highpower broadarea distributed Bragg reflector lasers, Optical and Quantum Electronics, 50 (2018), pp. 88/188/12, DOI 10.1007/s1108201712978 .
Abstract
We theoretically analyze the influence of nonlinear effects such as spatial holeburning, twophoton absorption and gain compression on the power?current and beam characteristics of a highpower broadarea 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 twophoton absorption and gain compression, on the other hand, excitation of higher order lateral modes leads to losses through the Bragg grating. In combination with spatiotemporal power variations resolved by the utilized timedependent traveling wave model twophoton 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. 380390, 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 travelingwave 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 travelingwave 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 broadarea edgeemitting semiconductor devices, Int. J. High Perform. Comput. Appl., 32 (2018), pp. 512522, DOI 10.1177/1094342016677086 .
Abstract
We present a (2+1)dimensional partial differential equation model for spatiallateral dynamics of edgeemitting broadarea semiconductor devices and several extensions of this model describing different physical effects. MPIbased parallelization of the resulting middlesize numerical problem is implemented and tested on the blade cluster and separate multicore computers at the Weierstrass Institute in Berlin. It was found, that an application of 2530 parallel processes on all considered platforms was guaranteeing a nearly optimal performance of the algorithm with the speedup around 2025 and the efficiency of 0.70.8. It was also shown, that a simultaneous usage of several inhouse available multicore 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 timedelay dynamical systems, Physical Review Letters, 118 (2017), pp. 193901/1193901/6.
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 nearfield width of highpower broadarea diode lasers, Applied Physics Letters, 110 (2017), pp. 263504/1263504/5, DOI 10.1063/1.4990531 .
Abstract
Typical for broadarea laser (BAL) diodes operating in a continuouswave mode is a narrowing of the nearfield (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 selfheating 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 currentdependent 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 threedimensional thermoelectrooptic simulations indicate that a longitudinally homogeneous device temperature can reduce the frontfacet 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 selfmobile cavity solitons in a wideaperture laser with a saturable absorber, Chaos. An Interdisciplinary Journal of Nonlinear Science, 27 (2017), pp. 114304/1114304/9.
Abstract
We investigate the spatiotemporal dynamics of cavity solitons in a broad area verticalcavity surfaceemitting laser with saturable absorption subjected to timedelayed 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 modelocking regime in a broadarea 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 electrooptical models for broadarea edgeemitting semiconductor devices, Optical and Quantum Electronics, 49 (2017), pp. 332/1332/8, DOI 10.1007/s1108201711683 .
Abstract
We extend a 2 (space) + 1 (time)dimensional traveling wave model for broadarea edgeemitting 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 edgeemitting lasers based on strained germanium, Optical and Quantum Electronics, 48 (2016), pp. 156/1156/7, DOI 10.1007/s1108201603944 .
Abstract
We consider a device concept for edgeemitting 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 twodimensional description. The twodimensional 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 ShockleyReadHall 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. 245432/1245432/13, 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 secondorder 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 meanfield GrossPitaevskii 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 modelocked lasers with coherent dual mode optical injection: Simulations, analysis and experiment, Journal of the Optical Society of America. B, 33 (2016), pp. 351359.
Abstract
Using a delay differential equations model we study the dynamics of a passively modelocked 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. 041801/1041801/5.
Abstract
We report a destabilization mechanism of localized solutions in spatially extended systems which is induced by delayed feedback. Considering a model of a wideaperture 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 delayinduced 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 lowfrequency fluctuations in the direction of the soliton motion. The same type of modulational instability is demonstrated for localized solutions of the cubicquintic complex GinzburgLandau equation. 
M. Radziunas, Modeling and simulations of broadarea edgeemitting 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 spatiallateral dynamics of edgeemitting broadarea semiconductor devices and several extensions of this model describing different physical effects. MPIbased parallelization of the resulting middlesize numerical problem is implemented and tested on the blade cluster and separate multicore computers at the Weierstrass Institute in Berlin. It was found, that an application of 2530 parallel processes on all considered platforms was guaranteeing a nearly optimal performance of the algorithm with the speedup around 2025 and the efficiency of 0.70.8. It was also shown, that a simultaneous usage of several inhouse available multicore 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 multimode delay differential equation model for lasers with optical feedback, Optical and Quantum Electronics, 48 (2016), pp. 19, DOI 10.1007/s1108201607362 .
Abstract
In this paper, we discuss the relations between the spatiallydistributed traveling wave, LangKobayashi, and a new multimode delay differential equation models for FabryPerot 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 LangKobayashi type model is in good agreement with the traveling wave model only for the small feedback regimes, whereas newly derived multimode delay differential equation model remains correct even at moderate and large optical feedback regimes. 
M. Radziunas, New multimode delay differential equation model for lasers with optical feedback, Optical and Quantum Electronics, 48 (2016), pp. 470/1470/9, DOI 10.20347/WIAS.PREPRINT.2294 .
Abstract
In this paper, we discuss the relations between the spatiallydistributed traveling wave, LangKobayashi, and a new multimode delay differential equation models for FabryPerot 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 LangKobayashi type model is in good agreement with the traveling wave model only for the small feedback regimes, whereas newly derived multimode 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 passivelymodelocked semiconductor lasers subject to optical feedback: A semianalytic approach, Physical Review A, 92 (2015), pp. 053807/1053807/11.
Abstract
We propose a semianalytical method of calculating the timing fluctuations in modelocked 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 frequencypulling region forms about the main resonances, within which a timing jitter reduction is observed. The width of these frequencypulling 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 flatmirror verticalexternalcavity surfaceemitting lasers by spatiotemporal modulation of the pump profile, Physical Review A, 92 (2015), pp. 043829/1043829/8.
Abstract
We propose and demonstrate theoretically that verticalexternalcavity surfaceemitting 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 patternforming 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 externalcavity length. In particular, the stabilization method is shown to operate most efficiently in ClassA laser limit (for relatively long VECSEL resonators), while it becomes ineffective in ClassB 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 microintegrated external cavity diode lasers, Optical and Quantum Electronics, 47 (2015), pp. 14591464.

M. Radziunas, R. Herrero, M. Botey, K. Staliunas, Farfield narrowing in spatially modulated broadarea edgeemitting semiconductor amplifiers, Journal of the Optical Society of America. B, 32 (2015), pp. 9931000.
Abstract
We perform a detailed theoretical analysis of the far field narrowing in broadarea 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 microintegrated externalcavity diode lasers: Simulations, analysis and experiments, IEEE J. Quantum Electron., 51 (2015), pp. 2000408/12000408/8.
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 edgeemitting and ring semiconductor lasers, Optical and Quantum Electronics, 47 (2015), pp. 13191325.
Abstract
We use the traveling wave model for simulating and analyzing nonlinear dynamics of multisection ring and edgeemitting 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 twosection semiconductor laser, Phys. Rev. E (3), 89 (2014), pp. 052903/1052903/7.
Abstract
The effect of coherenct single frequency injection in twosection semiconductor lasers is studied numerically using a model based on a set of delay differential equations. The existence of bistability between different CW and nonstationary 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 nonuniform 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. 303314.

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. 20140101/120140101/18.
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 VerticalCavity SurfaceEmitting 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 timedelayed optical feedback and investigate analytically the role of the phase of the feedback and the carrier lifetime on the selfmobility properties of the localized structures. We show that these two parameters affect strongly the space time dynamics of twodimensional 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. PérezSerrano, J. Javaloyes, S. Balle, Directional reversals and multimode dynamics in semiconductor ring lasers, Physical Review A, 89 (2014), pp. 023818/1023818/14.
Abstract
We investigate the dynamics of longitudinal modes in quantumwell semiconductor ring lasers by means of a spatiotemporal 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. 627646.

R.M. Arkhipov, A. Pimenov, M. Radziunas, A.G. Vladimirov, D. Arsenjević, D. Rachinskii, H. Schmeckebier, D. Bimberg, Hybrid modelocking in edgeemitting semiconductor lasers: Simulations, analysis and experiments, IEEE J. Select. Topics Quantum Electron., 19 (2013), pp. 1100208/11100208/6.
Abstract
Hybrid modelocking in a two section edgeemitting 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 modelocking 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 modelocked laser fP . Finally, we provide an experimental demonstration of hybrid modelocking in a 20 GHz quantumdot laser with the modulation frequency of the reverse bias applied to the absorber section close to fP =2. 
A. PérezSerrano, J. Javaloyes, S. Balle, Multichannel wavelength conversion using fourwave mixing in semiconductor ring lasers, IEEE Phot. Tech. Letter, 25 (2013), pp. 476479.
Abstract
We theoretically study alloptical simultaneous wavelength conversion of multiple channels by fourwave mixing in semiconductor ring lasers. Locking the semiconductor ring laser to a holding beam allows to achieve large conversion efficiencies with good signaltonoise ratio in several channels at multiGb/s bit rates. Crosstalk between signals, arising from the peculiar fourwave mixing cascade of modes in semiconductor ring lasers and their crossgain 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. PérezSerrano, J. Javaloyes, S. Balle, Spectral delay algebraic equation approach to broad area laser diodes, IEEE J. Select. Topics Quantum Electron., 19 (2013), pp. 1502808/11502808/8.

A. Pimenov, A.G. Vladimirov, S.V. Gurevich, K. Panajotov, G. Huyet, M. Tlidi, Delayed feedback control of selfmobile cavity solitons, Physical Review A, 88 (2013), pp. 053830/1053830/11.
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 timedelayed optical feedback and carrier lifetime on the selfmobility 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 noninstantaneous 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. 132101/1132101/4.
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 electronelectron scattering in quantum dot materials, Phys. Rev. B., 88 (2013), pp. 235421/1235421/11.
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 BornMarkov approximation, in which the numerical evaluation of high dimensional integrals is done via a quasiMonte 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 modelocked lasers, Optics Express, 21 (2013), pp. 1924019251.

R. Čiegis, A. Mirinavičius, M. Radziunas, Comparison of split step solvers for multidimensional Schrödinger problems, Computational Methods in Applied Mathematics, 13 (2013), pp. 237250.
Abstract
Hybrid modelocking in a two section edgeemitting 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 modelocking 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 modelocked laser fP . Finally, we provide an experimental demonstration of hybrid modelocking in a 20 GHz quantumdot 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 multistripe laser array with external offaxis feedback, Journal of the Optical Society of America. B, 30 (2013), pp. 16061613.
Abstract
We study theoretically the dynamics of a multistripe laser array with an external cavity formed by either a single or two offaxis 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 antiphase oscillating intensities of the two counterpropagating 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 threedimensional reservoirs to quantum dot states, physica status solidi (c), 9 (2012), pp. 12781281.

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 modelocked laser, Optics Express, 20 (2012), pp. 2557225583.

M. Lichtner, V.Z. Tronciu, A.G. Vladimirov, Theoretical investigations of striped and nonstriped broad area lasers with offaxis feedback, IEEE J. Quantum Electron., 48 (2012), pp. 353360.

M. Tlidi, E. Averlant, A.G. Vladimirov, K. Panajotov, Delay feedback induces a spontaneous motion of twodimensional cavity solitons in driven semiconductor microcavities, Physical Review A, 86 (2012), pp. 033822/1033822/8.

D. Turaev, A.G. Vladimirov, S. Zelik, Long range interaction and synchronization of oscillating dissipative solitons, Physical Review Letters, 108 (2012), pp. 263906/1263906/5.

M. Radziunas, A.G. Vladimirov, E.A. Viktorov, G. Fiol, H. Schmeckebier, D. Bimberg, Pulse broadening in quantumdot modelocked semiconductor lasers: Simulation, analysis and experiments, IEEE J. Quantum Electron., 47 (2011), pp. 935943.
Abstract
We consider a modelocked quantumdot edgeemitting 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 modelocking 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 modelocked 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. 105401/1105401/8.
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 nearlyperiodic transitions between neighboring cavity mode determined continuous wave states with increasing injection current. 
I. Babushkin, U. Bandelow, A. Vladimirov, Rotational symmetry breaking in smallarea circular vertical cavity surface emitting lasers, Optics Communications, 284 (2011), pp. 12991302.
Abstract
We investigate theoretically the dynamics of three loworder transverse modes in a smallarea 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 quantumdot VCSELs, Photonics and Nanostructures  Fundamentals and Applications, 9 (2011), pp. 337344.

N. Rebrova, G. Huyet, D. Rachinskii, A.G. Vladimirov, Optically injected modelocked laser, Phys. Rev. E (3), 83 (2011), pp. 066202/1066202/8.

M. Radziunas, K. Staliunas, Spatial ``rocking'' in broadarea semiconductor lasers, Europhysics Letters, 95 (2011), pp. 14002/114002/6.
Abstract
The spatial “rocking” is a dynamical effect converting a phaseinvariant oscillatory system into a phasebistable 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 phasebistable spatially extended pattern forming systems. 
V.Z. Tronciu, C. Mirasso, P. Colet, M. Hamacher, M. Benedetti, V. Vercesi, V. AnnovazziLodi, Chaos generation and synchronization using an integrated source with an air gap, IEEE J. Quantum Electron., 46 (2010), pp. 18401846.

V.Z. Tronciu, Chaos communication using semiconductor lasers subject to different kinds of optical feedback, Moldavian Journal of the Physical Sciences, 9 (2010), pp. 5069.

A.G. Vladimirov, U. Bandelow, G. Fiol, D. Arsenijević, M. Kleinert, D. Bimberg, A. Pimenov, D. Rachinskii, Dynamical regimes in a monolithic passively modelocked quantum dot laser, Journal of the Optical Society of America. B, 27 (2010), pp. 21022109.

R. Čiegis, M. Radziunas, Effective numerical integration of traveling wave model for edgeemitting broadarea 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. 409430.
Abstract
We consider a system of 1+2 dimensional partial differential equations which describes dynamics of edgeemitting 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. 809828.
Abstract
We present a microscopic theory describing the charge carrier and light emission dynamics in quantum dot (QD) light emitters. The theory covers nonclassical 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 electronphonon scattering rates between bound QD, continuous wetting layer (WL) and bulk states. In the low carrier density limit, multiphonon 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) timeresolved 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 verticalcavity surfaceemitting 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. 209214.
Abstract
We report results on experimental and numerical investigations of the output characteristics of edgeemitting 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 modelocking in a 40 GHz monolithic quantum dot laser, Applied Physics Letters, 96 (2010), pp. 011104/1011104/3.

J.E. Kim, E. Malic, M. Richter, A. Wilms, A. Knorr, MaxwellBloch equation approach for describing the microscopic dynamics of quantumdot surfaceemitting structures, IEEE J. Quantum Electron., 46 (2010), pp. 11151126.

M. SchulzRuhtenberg, I. Babushkin, N.A. Loiko, Th. Ackemann, K. Huang, Polarization properties in the transition from below to above lasing threshold in broadarea verticalcavity surfaceemitting lasers, Physical Review A, 81 (2010), pp. 023819/1023819/11.
Abstract
For highly divergent emission of broadarea verticalcavity surfaceemitting 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, nearthreshold and abovethreshold 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, NonPoissonian statistics in an optical analog of quantum billiard with perfectly square boundaries, Physics Letters A, 374 (2010), pp. 896900.
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 LangKobayashi system using the limit of large delay, SIAM Journal on Applied Dynamical Systems, 9 (2010), pp. 519535.

V.Z. Tronciu, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, Improving the stability of distributedfeedback tapered masteroscillator poweramplifiers, Optical and Quantum Electronics, 41 (2009), pp. 531537.
Abstract
We report theoretical results on the wavelength stabilization in distributedfeedback masteroscillator poweramplifiers 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. 462468.

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. 903923.
Abstract
We consider a onedimensional linear Schrödinger problem defined on an infinite domain and approximated by the CrankNicolson 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. 87498755.

A. Jechow, M. Lichtner, R. Menzel, M. Radziunas, D. Skoczowsky, A.G. Vladimirov, Stripearray diodelaser in an offaxis external cavity: Theory and experiment, Optics Express, 17 (2009), pp. 1959919604.
Abstract
Stripearray diode lasers naturally operate in an antiphase 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 stripearray laterally coupled by offaxis 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 distributedfeedback tapered masteroscillator poweramplifiers, IEEE J. Quantum Electron., 45 (2009), pp. 609616.

M. Radziunas, V.Z. Tronciu, U. Bandelow, M. Lichtner, M. Spreemann, H. Wenzel, Mode transitions in distributedfeedback tapered masteroscillator poweramplifier: Theory and experiments, Optical and Quantum Electronics, 40 (2008), pp. 11031109.
Abstract
Theoretical and experimental investigations have been carried out to study the spectral and spatial behavior of monolithically integrated distributedfeedback tapered masteroscillators poweramplifiers 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. 47474752.

V.Z. Tronciu, C.R. Mirasso, P. Colet, Chaosbased communications using onoff phase shift keying method, Moldavian Journal of the Physical Sciences, 7 (2008), pp. 343349.

V.Z. Tronciu, C.R. Mirasso, P. Colet, Chaosbased communications using semiconductor lasers subject to feedback from an integrated double cavity, Journal of Physics B: Atomic, Molecular and Optical Physics, 41 (2008), pp. 155401/1155401/8.

S. Yanchuk, K.R. Schneider, O. Lykova, Amplitude synchronization in a system of two coupled semiconductor lasers, Ukrainian Mathematical Journal, 60 (2008), pp. 426435.

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. 327348.

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. 136142.

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. 30004/130004/5.

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. 231116/1231116/3.

M. Radziunas, Numerical bifurcation analysis of the traveling wave model of multisection semiconductor lasers, Optical and Quantum Electronics, 213 (2006), pp. 98112.

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. 016209/1016209/7.

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 Qswitching in monolithic 40 GHz modelocked semiconductor lasers, Applied Physics Letters, 88 (2006), pp. 221104/1221104/3.

M. Nizette, D. Rachinskii, A. Vladimirov, M. Wolfrum, Pulse interaction via gain and loss dynamics in passive modelocking, Physica D. Nonlinear Phenomena, 218 (2006), pp. 95104.

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. 21352137.

D.I. Rachinskii, A. Vladimirov, U. Bandelow, B. Hüttl, R. Kaiser, Qswitching instability in a modelocked semiconductor laser, Journal of the Optical Society of America. B, 23 (2006), pp. 663670.

V.Z. Tronciu, H.J. Wünsche, M. Wolfrum, M. Radziunas, Semiconductor laser under resonant feedback from a FabryPerot resonator: Stability of continuouswave operation, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 73 (2006), pp. 046205/1046205/7.

E. Viktorov, P. Mandel, A. Vladimirov, U. Bandelow, A model for modelocking in quantum dot lasers, Applied Physics Letters, 88 (2006), pp. 201102/1201102/3.

U. Bandelow, M. Radziunas, A. Vladimirov, B. Hüttl, R. Kaiser, 40 GHz Modelocked semiconductor lasers: Theory, simulations and experiment, Optical and Quantum Electronics, 38 (2006), pp. 495512.

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. 181911/1181911/3.

A. Vladimirov, D. Turaev, Model for passive mode locking in semiconductor lasers, Physical Review A, 72 (2005), pp. 033808/1033808/13.

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. 363377.

A.G. Vladimirov, D.V. Turaev, G. Kozyreff, Delay differential equations for modelocked semiconductor lasers, , 29 (2004), pp. 12211223.

A.G. Vladimirov, D.V. Turaev, A new model for a modelocked semiconductor laser, Radiophysics and Quantum Electronics, 47 (2004), pp. 769776.

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. 016206/1016206/10.

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. 5166.

J. Sieber, L. Recke, K.R. Schneider, Dynamics of multisection semiconductor lasers, Journal of Mathematical Sciences (New York), 124 (2004), pp. 52985309.

K.R. Schneider, S. Yanchuk, L. Recke, Dynamics of two mutually coupled semiconductor lasers: Instantaneous coupling limit, Phys. Rev. E (3), 69 (2004), pp. 056221/1056221/12.

V. Tronciu, Investigation of selfpulsation and excitability of tandem blue lasers, AIUB Journal of Science and Engineering, 3 (2004), pp. 710.

O. Brox, S. Bauer, M. Radziunas, M. Wolfrum, J. Sieber, J. Kreissl, B. Sartorius, H.J. Wünsche, Highfrequency pulsations in DFBlasers with amplified feedback, Numerical Functional Analysis and Optimization. An International Journal, 39 (2003), pp. 13811387.

B. Krauskopf, K.R. Schneider, J. Sieber, S. Wieczorek, M. Wolfrum, Excitability and selfpulsations near homoclinic bifurcations in semiconductor laser systems, IEEE J. Quantum Electron., 215 (2003), pp. 367379.

H.J. Wünsche, M. Radziunas, S. Bauer, O. Brox, B. Sartorius, Simulation of phasecontrolled modebeating lasers, IEEE J. Select. Topics Quantum Electron., 9 (2003), pp. 857864.

U. Bandelow, R. Hünlich, Th. Koprucki, Simulation of static and dynamic properties of edgeemitting multiplequantumwell lasers, IEEE J. Select. Topics Quantum Electron., 9 (2003), pp. 798806.

A.G. Vladimirov, G. Kozyreff, P. Mandel, Synchronization of weakly stable oscillators and semiconductor laser arrays, Europhysics Letters, 61 (2003), pp. 613619.

A.G. Vladimirov, G. Kozyreff, P. Mandel, Synchronization of weakly stable oscillators and semiconductor laser arrays, Europhysics Letters, 61 (2003), pp. 613619.

H.J. Wünsche, O. Brox, M. Radziunas, F. Henneberger, Excitability of a semiconductor laser by a twomode homoclinic bifurcation, Physical Review Letters, 88 (2002), pp. 023901/1023901/4.

D. Turaev, M. Wolfrum, Instabilities of lasers with moderately delayed optical feedback, IEEE J. Quantum Electron., 213 (2002), pp. 127138.

U. Bandelow, M. Radziunas, J. Sieber, M. Wolfrum, Impact of gain dispersion on the spatiotemporal dynamics of multisection lasers, IEEE J. Quantum Electron., 37 (2001), pp. 183188.

M. Möhrle, B. Sartorius, C. Bornholdt, S. Bauer, O. Brox, A. Sigmund, R. Steingräber, M. Radziunas, H.J. Wünsche, Detuned grating multisectionRWDFB lasers for high speed optical signal processing, IEEE J. Select. Topics Quantum Electron., 7 (2001), pp. 217223.

V. Tronciu, H.J. Wünsche, J. Sieber, K.R. Schneider, Dynamics of single mode semiconductor lasers with passive dispersive reflectors, , 182 (2000), pp. 221228.

M. Radziunas, H.J. Wünsche, B. Sartorius, O. Brox, D. Hoffmann, K.R. Schneider, D. Marcenac, Modeling selfpulsating DFBlasers with an integrated phase tuning section, IEEE J. Quantum Electron., 36 (2000), pp. 10261034.
Contributions to Collected Editions

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: Realtime Measurements, Rogue Phenomena, and SingleShot Applications VI, D.R. Solli, G. Herink, S. Bielawski, eds., 11671 of Proceedings of SPIE, SPIE. Digital Library, 2021, pp. 116710D/1116710D/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 NozakiBekki 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/1116800N/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 broadarea lasers, in: 2021 27th International Semiconductor Laser Conference (ISLC), IEEE Xplore, IEEE, 2021, pp. 12, 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/1112740L/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 FabryPerot 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 offstate to a high current level. The lasing build up occurs at each roundtrip via a stepwise 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. GarreWerner, J.J. MontielPonsoda, V. Raab, G. Safont, C. Brée, M. Radziunas, C. Cojocaru, K. Staliunas, 1 kW cw fibercoupled diode laser with enhanced brightness, in: HighPower Diode Laser Technology XVIII, M.S. Zediker, ed., 11262 of Proceedings of SPIE, SPIE, San Francisco, 2020, pp. 1126202/11126202/9, DOI 10.1117/12.2546086 .
Abstract
We developed a 1kW cw fibercoupled diode laser at 9XX nm by using beam combining of eight high power diode laser bars. To achieve beam combining, we employ Lyotfiltered 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: Realtime Measurements, Rogue Phenomena, and SingleShot Applications V, D.R. Solli, G. Herink, S. Bielawski, eds., 11265 of Proceedings of SPIE, SPIE Digital Library, 2020, pp. 112650F/1112650F/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 FabryPerot 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, quasistatic 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 NozakiBekki holes previously predicted in the complex GinzburgLandau 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 SolidState Sciences, Springer, Cham, 2020, pp. 91133, DOI 10.1007/9783030356569_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 multisection 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 pumpprobe methods, twocolor fourwave mixing setups and quantumstate tomography. We discuss the optical nonlinearities resulting from lightmatter coupling and charge carrier interactions using microscopically motivated rateequation models. In the second part, nanostructured modelocked 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 modelocked 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 modelbased analysis of tapered broadarea 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/1112740I/10, DOI 10.1117/12.2537015 .
Abstract
We present simulation results showing the impact of a longitudinal linearly varying electrical contact width on intracavity intensity, carrier density and temperature distributions of broadarea lasers. In addition, the impact of index guiding trenches on these internal distributions is investigated. The simulations were performed using a timedependent 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 highpower 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/1113560W/14, DOI 10.1117/12.2559175 .
Abstract
Highpower broadarea diode lasers (BALs) exhibit chaotic spatiotemporal 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 electrooptical (EO) model for the optical field and carrier dynamics along the quantumwell active zone of the laser. Thereby we effectively couple the EO and heattransport (HT) solvers. Thermal lensing is included by a thermallyinduced contribution to the index profile. The heat sources obtained with the dynamic EOsolver 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 HTproblem, with timeaveraged 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 fewnslong 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 ElectroOptics (CLEO PR 2020), OSA Technical Digest, Optical Society of America, Washington, 2020, pp. C4C_4/1C4C_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. MontielPonsoda, G. GarreWerner, V. Raab, Simulation of cascaded polarizationcoupled systems of broadarea 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. 9798, DOI 10.1109/NUSOD49422.2020.9217764 .
Abstract
We present a brightness and powerscalable polarization beam combining scheme for highpower, broadarea semiconductor lasers. To achieve the beam combining, we employ Lyotfiltered 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 twofoureightsixteen 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 broadarea diode lasers, in: 2019 Conference on Lasers and ElectroOptics Europe and European Quantum Electronics Conference, OSA Technical Digest, IEEE, Piscataway, 2019, pp. 11, DOI 10.1109/CLEOEQEC.2019.8871622 .
Abstract
Modern highpower broadarea semiconductor laser diodes (BASLDs) deliver optical output powers of several ten Watts at high electrooptical 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 highpower, broadarea diode lasers: Modeling, simulations, and experiments, in: 2019 Conference on Lasers and ElectroOptics Europe and European Quantum Electronics Conference, OSA Technical Digest, IEEE, Piscataway, 2019, pp. 11, DOI 10.1109/CLEOEEQEC.2019.8871911 .
Abstract
Summary form only given. Recent improvements in design and development have significantly increased the relevance of highpower, broadarea laser diodes and laser diode bars in the market for industrial, highbrightness 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 timedomain 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 halfwave 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. 712, DOI 10.1007/9783030252618_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?Landautype 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 timedelay 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. 14, 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 nonperiodic, and showed that they are closely connected to NozakiBekki holes previously predicted in the complex GinzburgLandau equation. 
U. Gowda, S. Slepneva, A. Pimenov, A.G. Vladimirov, E. Viktorov, G. Huyet, Stable and unstable NozakiBekki 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/1109120M/6, DOI 10.1117/12.2510300 .
Abstract
Long cavity fibrebased wavelength sweeping lasers are promising devices with a wide range of potential applications ranging from communications to life sciences. For example, Fourier Domain ModeLocked (FDML) lasers, which are commonly used for Optical Coherence Tomography (OCT) imaging applications are long cavity lasers incorporating an intracavity 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 intracavity 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 NozakiBekki holes (NBH) that circulate in the laser cavity. As a function of the injection current, the laser could operate in various regimes including bistability 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 multiwavelength 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. 7576.
Abstract
We show simulation results of a compact, integrated and tunable multiwavelength 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 allpassive 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. 712, DOI 10.1007/9783030252618_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 GinzburgLandautype 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 timedelay 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 modelocked 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. 1068226/11068226/6.

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 2427, 2018, S. Andronic, ed., Technical University of Moldova, 2018, pp. 105108.
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 continuouswave 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 highpower broadarea 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/1105261H/10, DOI 10.1117/12.2289803 .
Abstract
The effect of current spreading on the lateral farfield divergence of highpower broadarea lasers is investigated with a timedependent 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 driftdiffusion approach, however, the injected current density is obtained from the gradient of the quasiFermi potential of the holes, which solves a Laplace equation in the pdoped 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 farfield divergence is obtained. We conclude that an advanced modeling of the profiles of the injection current densities is necessary for a correct description of farfield blooming in broadarea lasers. 
M. Radziunas, U. Bandelow, C. Brée, V. Raab, H. Wenzel, A. Zeghuzi, Modeling and simulation of highpower broadarea semiconductor lasers with optical feedback from different external cavities, in: 2018 IEEE International Semiconductor Laser Conference (ISLC 2018), Santa Fe, New Mexico, USA, 1619 September 2018, Institute of Electrical and Electronics Engineers, Inc. (IEEE), 2018, pp. SuA4/1SuA4/2.

M. Radziunas, J. Fuhrmann, A. Zeghuzi, H.J. Wünsche, Th. Koprucki, H. Wenzel, U. Bandelow, Efficient coupling of heat flow and electrooptical models for simulation of dynamics in highpower broadarea 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. 9192.

M. Kantner, U. Bandelow, Th. Koprucki, H.J. Wünsche, Simulation of quantum dot devices by coupling of quantum master equations and semiclassical 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. 217218.

A. Zeghuzi, M. Radziunas, A. Klehr, H.J. Wünsche, H. Wenzel, A. Knigge, Influence of nonlinear effects on the characteristics of pulsed highpower 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. 233234.

M. Radziunas, A. Zeghuzi, J. Fuhrmann, Th. Koprucki, H.J. Wünsche, H. Wenzel, U. Bandelow, Efficient coupling of inhomogeneous current spreading and electrooptical models for simulation of dynamics in broadarea 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. 231232.

M. Kantner, U. Bandelow, Th. Koprucki, H.J. Wünsche, Modeling and simulation of injection dynamics for quantum dot based singlephoton 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. 219220.
Abstract
Single semiconductor quantum dots embedded in pin diodes have been demonstrated to operate as electrically driven singlephoton 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 oxideconfined PNdiodes, 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. 215216.
Abstract
Current injection into single quantum dots embedded in vertical pndiodes featuring oxide apertures is essential to the technological realization of singlephoton sources. This requires efficient electrical pumping of submicron 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 pindesign in the lowinjection regime suitable for singlephoton emitters. By an alternative design employing pdoping 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 flatmirror 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. 989406/1989406/7.
Abstract
We show that modulation instability (MI) can be suppressed in vertical external cavity surface emitting lasers (VECSELs) by introducing a periodic spatiotemporal modulation of the pump profile which in turn allows a simple flatmirror configuration. The stability analysis of such pump modulated flatmirror 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 micrometerlong 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/197420K/7.
Abstract
A novel, timeresolved interferometric technique is presented allowing the reconstruction of the complex electric field output of a fast frequency swept laser in a singleshot 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 timeresolved realtime 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. 139151.
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 BespalovTalanov 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 modelocked lasers and passive cavities, in: Laser Optics (LO), 2016 International Conference, IEEE, New York, 2016, pp. 37628.
Abstract
We study interaction of wellseparated 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 multimode 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. 1314.
Abstract
In this work, we introduce a new multimode (MM) delay differential equation (DDE) model suited for simulations of the FabryPerot type diode laser with an optical feedback from the external cavity (EC). 
M. Radziunas, Modeling and simulations of edgeemitting broadarea semiconductor lasers and amplifiers, in: Parallel Processing and Applied Mathematics  11th International Conference, PPAM 2015 Krakow, Poland, September 69, 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. 269276.
Abstract
A (2+1)dimensional partial differential equation model describing spatiallateral dynamics of edgeemitting broadarea semiconductor devices is considered. A numerical scheme based on a splitstep 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 ElectroOptics Europe & European Quantum Electronics Conference (Cleo/EuropeEQEC), IEEE, New York, 2017, DOI 10.1109/CLEOEEQEC.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/198920I/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 PhotoOptical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only. 
M. Kantner, U. Bandelow, Th. Koprucki, Multiscale modeling and simulation of singlephoton sources, in: Proceedings of iNOW 2015 (International NanoOptoelectronics Workshop) (PDF only), Y. Arakawa, F. Koyama, C. ChangHasnain, D. Bimberg, eds., pp. 129130.

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. 14.
Abstract
Semiconductor lasers are efficient light sources with an important drawback, the lack of an intrinsic mode selection mechanism which leads to spatiotemporal 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 VerticalCavity SurfaceEmitting 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. 5859.

M. Radziunas, R. Herrero, M. Botey, K. Staliunas, Beam shaping in spatially modulated broad area edgeemitting semiconductor lasers, in: 2015 European Conference on Lasers and ElectroOptics  European Quantum Electronics Conference, Optical Society of America, 2015, paper CB_P_3, 2015, pp. 11.

M. Radziunas, V. Tronciu, E. Luvsandamdin, Ch. Kürbis, A. Wicht, H. Wenzel, Coexistence of multiple stable continuouswave states in microintegrated externalcavity diode lasers, in: 2015 European Conference on Lasers and ElectroOptics  European Quantum Electronics Conference, Optical Society of America, 2015, paper CB_P_28, 2015, pp. 11.

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. 9497.

R.M. Arkhipov, M. Radziunas, A.G. Vladimirov, Theoretical analysis of the influence of external periodic forcing on nonlinear dynamics of passively modelocked 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. 36.

R.M. Arkhipov, M.V. Arkhipov, Modelocking 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. 4345.

M. Kantner, Th. Koprucki, H.J. Wünsche, Numerical simulation and optimization of electrical resistance in distributed Bragg reflectors, in: iNOW2014  International NanoOptoelectronics Workshop, Luga and St. Petersburg, Russia, August 1022, 2014, C. ChangHasnain, Z.I. Alferov, V.G. Dubrovskii, eds., Polytechnical University St. Petersburg, 2014, pp. 8990.

M. Radziunas, R. Ciegis, Modeling and simulations of beam stabilization in edgeemitting broad area semiconductor devices, in: Parallel Processing and Applied Mathematics  10th International Conference, PPAM 2013, Warsaw, Poland, September 811, 2013, Revised Selected Papers, Part II, R. Wyrzykowski, J. Dongarra, K. Karczewski, J. Waśniewski, eds., LNCS 8385, Springer, Heidelberg, 2014, pp. 332342.
Abstract
A 2+1 dimensional PDE traveling wave model describing spatiallateral dynamics of edgeemitting broad area semiconductor devices is considered. A numerical scheme based on a splitstep 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 edgeemitting 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/191340Q/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 spatiotemporal 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. 4547.

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 1619, 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. 243256.

U. Bandelow, Th. Koprucki, H.J. Wünsche, Dynamics of classical optical fields in semiconductor lasers, in: iNOW2014  International NanoOptoelectronics Workshop, Luga and St. Petersburg, Russia, August 1022, 2014, C. ChangHasnain, Z.I. Alferov, V.G. Dubrovskii, eds., Polytechnical University St. Petersburg, 2014, pp. 1415.

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, 14 September 2014, J. Piprek, J. Javaloyes, eds., IEEE Conference Publications Management Group, Piscataway, NJ, USA, 2014, pp. 149150.

M. Radziunas, Longitudinal mode analysis of multisection ring and edgeemitting semiconductor lasers, in: Proceedings of the 14th International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD 2014, 14 September 2014, J. Piprek, J. Javaloyes, eds., IEEE Conference Publications Management Group, Piscataway, NJ, USA, 2014, pp. 133134.

M. Radziunas, Simulations and analysis of beam shaping in spatially modulated broad area edgeemitting devices, in: Proceedings of 24th IEEE International Semiconductor Laser Conference (ISLC 2014), Palma de Mallorca, Spain, Sept. 710, 2014, 2014, pp. 1920.

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, 1922 August 2013, J. Piprek, L. Chrostowski, eds., IEEE Conference Publications Management Group, Piscataway, NJ, USA, 2013, pp. 117118.

R.M. Arkhipov, M. Radziunas, A.G. Vladimirov, Numerical simulations of the influence of injection of biharmonic radiation on the regime of passive modelocking in semiconductor laser, in: Proceedings of the XIVth AllRussian Scientific SchoolSeminar ``Physics and Microwave Application'' (Waves2013), Moscow, May 2026, 2013, Section 5: Nonlinear Dynamics and Information Systems (electronic, in Russian), 2013, pp. 912.

R.M. Arkhipov, A. Pimenov, M. Radziunas, A.G. Vladimirov, Theoretical analysis of hybrid and dual mode injected semiconductor modelocked lasers, in: Proceedings of the 2013 International NanoOptoelectronics Workshop (iNOW2013), Cargèse, France, August 1830, 2013, pp. B3B4.

M. Radziunas, R. Herrero, M. Botey, K. Staliunas, Theoretical study of beam quality improvement in spatially modulated broad area edgeemitting devices, in: CLEO/Europe  IQEC 2013 Conference Digest, OSA Technical Digest (CD) (Optical Society of America, 2013), paper CBP.38 MON, 2013, pp. 11.

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 CBP.37 MON, 2013, pp. 11.

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 914, 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 lightinduced spacial periodic structures, in: Proceedings of the XIVth AllRussian Scientific SchoolSeminar ``Physics and Microwave Application'' (Waves2013), Moscow, May 2026, 2013, Section 6: Coherent and Nonlinear Optics (electronic, in Russian), 2013, pp. 69.

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 IG2.4 WED, 2013, pp. 11.

U. Bandelow, Th. Koprucki, K. Gärtner, A. Wilms, A. Mielke, Comprehensive mathematical modeling and simulation of semiconductor lasers, in: Proceedings of the 2013 International NanoOptoelectronics Workshop (iNOW2013), Cargèse, France, August 1830, 2013, pp. A7A8.

U. Bandelow, N. Akhmediv, Solitons on a background, rogue waves, and classical soliton solutions of the SasaSatsuma equation, in: Laser Dynamics and Nonlinear Photonics, 2013 Sixth ``Rio De La Plata'' Workshop on, C. Masoller, I. Brener, eds., IEEE, 2013, pp. 12.

A. Pimenov, G. Kozyreff, V.Z. Tronciu, A.G. Vladimirov, Theoretical analysis of a multistripe laser array with external offaxis 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. 843212/1843212/10.

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/184320Q/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/184321D/6.

C. Brée, S. Amiranashvili, U. Bandelow, Spatiotemporal 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. 131132.

A.G. Vladimirov, D. Rachinskii, M. Wolfrum, Modeling of passively modelocked semiconductor lasers, in: Nonlinear Laser Dynamics: From Quantum Dots to Cryptography, K. Lüdge, ed., Reviews in Nonlinear Dynamics and Complexity, WILEYVCH Verlag GmbH & Co. KGaA, Weinheim, 2012, pp. 183216.

M. Radziunas, A.G. Vladimirov, E.A. Viktorov, G. Fiol, H. Schmeckebier, D. Bimberg, Strong asymmetry of modelocking pulses in quantumdot semiconductor lasers, in: CLEO/Europe and EQEC 2011 Conference Digest, OSA Technical Digest (CD) (Optical Society of America, 2011), paper CB3_5, pp. 11.

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. 11.

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 2224, 2011, Moldova, V. Kanter, I. Balmus, eds., 1, Technical University of Moldova, 2011, pp. 402403.

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 2224, 2011, Moldova, V. Kanter, I. Balmus, eds., 1, Technical University of Moldova, 2011, pp. 404405.

C. Brée, A. Demircan, G. Steinmeyer, Saturation of the alloptical Kerr effect, in: CLEO/Europe and EQEC 2011 Conference Digest, OSA Technical Digest (CD) (Optical Society of America, 2011), paper EF4_6, pp. 11.

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 2224, 2011, Moldova, V. Kanter, I. Balmus, eds., 1, Technical University of Moldova, 2011, pp. 2932.

V.Z. Tronciu, On the dynamics of multimode semiconductor lasers, in: Proceeding of the 7th International Conference on Microelectronics and Computer Science, Chisinau, September 2224, 2011, Moldova, V. Kanter, I. Balmus, eds., 1, Technical University of Moldova, 2011, pp. 2728.

M. Radziunas, A.G. Vladimirov, E.A. Viktorov, Traveling wave modeling, simulation and analysis of quantumdot modelocked 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/177200X/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. 7376.

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. 7780.

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. 6772.

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, YOSC2009, V. Karassik, ed., Bauman Moscow State Technical University Press, 2010, pp. 106109.

A. Jechow, D. Skoczowsky, M. Lichtner, M. Radziunas, R. Menzel, Highbrightness emission from stripearray broad area diode lasers operated in offaxis external cavities, in: HighPower Diode Laser Technology and Applications VIII, M.S. Zediker, ed., 7583 of Proceedings of SPIE, SPIE, 2010, pp. 758312/1758312/11.

A.G. Vladimirov, M. Wolfrum, G. Fiol, D. Arsenijević, D. Bimberg, E. Viktorov, P. Mandel, D. Rachinskii, Locking characteristics of a 40GHz hybrid modelocked 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/177200Y/8.

M. Radziunas, A.G. Vladimirov, E. Viktorov, Traveling wave modeling of modelocked quantum dot semiconductor lasers, in: CLEO/Europe and EQEC 2009 Conference Digest (Optical Society of America, 2009), oral presentation CB4.4 TUE, 2009, pp. 11.

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. 11.

V.Z. Tronciu, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, Calculation of improved features of distributedfeedback tapered masteroscillator poweramplifiers, in: CLEO/Europe and EQEC 2009 Conference Digest (Optical Society of America, 2009), poster CB.P.30 TUE, 2009, pp. 11.

V.Z. Tronciu, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, Dynamics and stability improvement of DFB tapered masteroscillator poweramplifiers, in: Proceedings of the 6th International Conference on Microelectronics and Computer Science, Chisinau, Moldova, October 13, 2009, I.M. Tiginyanu, I. Balmus, eds., Technical University of Moldova, Chisinau, 2009, pp. 1518.

V.Z. Tronciu, M. Lichtner, M. Radziunas, U. Bandelow, H. Wenzel, Improving the stability of distributedfeedback tapered masteroscillator poweramplifiers, 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. 5556.

M. SchulzRuhtenberg, I. Babushkin, N.A. Loiko, K.F. Huang, T. Ackemann, Analysis of polarization states of broadarea verticalcavity surfaceemitting lasers below and above threshold, in: 2009 IEEE/LEOS Winter Topicals Meeting Series (WTM 2009), IEEE, 2009, pp. 178179.

E.V. Viktorov, P. Mandel, A.G. Vladimirov, M. Wolfrum, G. Fiol, M. Kuntz, D. Bimberg, Hybrid modelocking 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. 11.

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/169971B/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. 6566.

M. Radziunas, U. Troppenz, J. Kreissl, Tailoring singlemode DFB laser with integrated passive feedback section for direct modulation applications, in: Proceedings of the European Conference on Lasers and ElectroOptics, 2007, and the International Quantum Electronics Conference. CLEO/IQEC 2007 (oral presentation CB35WED), IEEE, 2007, pp. 11.

J. Kreissl, U. Troppenz, W. Rehbein, T. Gärtner, P. Harde, M. Radziunas, 40 Gbit/s directly modulated passive feedback laser with complexcoupled DFB section, in: Proceedings of ECOC 2007, VDE Verlag GmbH, Berlin/Offenbach, 2007, pp. 213214.

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 ElectroOptics, 2007, and the International Quantum Electronics Conference. CLEO/IQEC 2007 (oral presentation JSI32THU), IEEE, 2007, pp. 11.

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. SchimanskyGeier, B. Fiedler, J. Kurths, E. Schöll, eds., World Scientific, New Jersey [et al.], 2007, pp. 185212.

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 ElectroOptics, 2007, and the International Quantum Electronics Conference. CLEO/IQEC 2007 (oral presentation IG62THU), IEEE, 2007, pp. 11.

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 ElectroOptics, 2007, and the International Quantum Electronics Conference. CLEO/IQEC 2007 (oral presentation IG63THU), IEEE, 2007, pp. 11.

M. Radziunas, H.J. Wünsche, B. Krauskopf, M. Wolfrum, External cavity modes in LangKobayashi 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/161840X/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 Tu3.1.5/1Tu3.1.5/2.

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. Th4.5.5/1Th4.5.5/2.

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 2529, 2005, 3, Institution of Electrical Engineers, London, 2005, pp. 677678.

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 1922, 2005, H.J. Wünsche, J. Piprek, U. Bandelow, H. Wenzel, eds., IEEE, Piscataway, NJ, 2005, pp. 2930.

U. Troppenz, M. Hamacher, M. Radziunas, H. Heidrich, Optical switching of clockwise/anticlockwise 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 ENOC2005 Fifth EUROMECH Nonlinear Dynamics Conference, Eindhoven, The Netherlands, August 712, 2005, D.H. VAN Campen, M.D. Lazurko, W.P.J.M. caps">caps">van der Oever, eds., 2005, pp. 20692073.

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. 5162.

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. 6370.

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. 112113.

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. 480489.

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. 7082.

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. 3537.

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. 377390.

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. 2737.

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, NUSOD02, Zürich, Switzerland, September 2527, 2002, A. Tarraf, J. Daleiden, F. Römer, C. Prott ET AL., eds., 2002, pp. 2627.

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. 420428.

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. 536545.
Preprints, Reports, Technical Reports

A.G. Vladimirov, Nonlocal and local temporal cavity soliton interaction in delay models of modelocked lasers, Preprint no. 2894, WIAS, Berlin, 2021, DOI 10.20347/WIAS.PREPRINT.2894 .
Abstract, PDF (949 kByte)
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 modelocked laser are derived and analyzed. It is shown that nonlocal pulse interaction due to gain depletion and recovery can lead either to a development of harmonic modelocking 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 antiphase or inphase stationary or breathing harmonic modelocking regime. 
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, Preprint no. 2724, WIAS, Berlin, 2020, DOI 10.20347/WIAS.PREPRINT.2724 .
Abstract, PDF (2735 kByte)
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 round trip and simulating its dynamics using a timedelayed model, we discuss the reasons for longterm sustainability of these solutions. We suggest that the observed dropouts are closely related to the coherent structures of the cubic complex GinzburgLandau equation. 
A.V. Kovalev, P.S. Dmitriev, A.G. Vladimirov, A. Pimenov, G. Huyet, E.A. Viktorov, Bifurcation structure of a swept source laser, Preprint no. 2681, WIAS, Berlin, 2020, DOI 10.20347/WIAS.PREPRINT.2681 .
Abstract, PDF (602 kByte)
We numerically analyze a delay differential equation model of a shortcavity 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 narrowband filter, there exist two bursting cycles determined by different parts of a continuouswave solutions branch.
Talks, Poster

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

U. Bandelow, Modeling and simulation of the dynamics in semiconductor lasers (online talk), GAMM 2021 (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 polarizationcoupling of highpower broadarea 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 timedelay laser models (online talk), Dynamics Days Europe 2021 Conference (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, Nanotechnology, 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, lightmatter interactions'', Australian National University, Canberra, Australia, February 14, 2020.

U. Bandelow, Dynamics of highpower 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, Nonisothermal ScharfetterGummel scheme for electrothermal 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 highpower broadarea semiconductor lasers, final EffiLas/HoTLas project meeting, Jenoptik Berlin, March 4, 2020.

M. Radziunas, Simulation of cascaded polarizationcoupled systems of broadarea 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 broadarea diode lasers, CLEO/EuropeEQEC 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 highpower, broadarea diode lasers: Modeling, simulations, and experiments, CLEO/EuropeEQEC 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, ZuseInstitut Berlin, February 15, 2019.

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

U. Bandelow, Selfconsistent thermaloptoelectronic model for the dynamics in highpower 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 highpower 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 highpower broadarea semiconductor lasers, Hotlas/Effilas project meeting, FerdinandBraunInstitut, 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 (MURPHYSHSFS2018), 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. WEHeraeus 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 NonHermitian 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 electrooptical models for simulation of dynamics in highpower broadarea 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 longitudinallateral periodic modulation of BALs to the quality of emitted beam, Project meeting of the BMBFEffiLas/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 highpower 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 highpower broad area lasers with PhC filtering element, EUROSTARS project E!10524 HIPLasers meeting, May 22  23, 2018, Femtika, Vilnius, Lithuania, May 22, 2018.

M. Radziunas, Modeling and simulation of highpower broadarea 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 broadarea 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, Timedelay 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, Timedelay systems in multimode laser dynamics, 675. WEHeraeusSeminar ,,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, Timedelay models of multimode 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, EFFILASHotLas project meeting, Jenoptik Diode Lab GmbH, Berlin, April 27, 2017.

S. Pickartz, Cancellation of Raman selffrequency 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 highpower broad area lasers, HiPLasers project meeting, RaabPhotonic GmbH, Potsdam, May 30, 2017.

M. Radziunas, Efficient coupling of inhomogeneous current spreading and electrooptical models for simulation of dynamics in broadarea 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 highpower broad area lasers with PhC filtering element, EUROSTARS HiPLaser project meeting, Monocrom, Vilanova, Barcelona, Spain, November 6, 2017.

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

A.G. Vladimirov, Mathematical modeling of dispersive and diffractive multimode lasers, 1st SinoGerman 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 singlephoton 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 onchip 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, MurphysHSFS 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 multimode 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 multimode 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 broadarea edgeemitting 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 highpower broad area lasers, Kickoff meeting of the EUROSTARS project HIPLasers, Monocrom S. L., Vilanova, Barcelona, Spain, October 14, 2016.

M. Radziunas, Modeling and simulations of broadarea edgeemitting semiconductor devices, EffiLASHotLas Kickoff meeting, Jenoptik Diode Lab GmbH, Berlin, September 14, 2016.

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

A.G. Vladimirov, Delay differential equation models in multimode 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 modelocked 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, SaintPetersburg State University, SaintPetersburg, Russian Federation, January 12, 2016.

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

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

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

A. Pimenov, Theoretical investigation of multimode dynamics and modelocking 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 ``Delayequations 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 TRUMPFFBHWIAS, FerdinandBraunInstitut, Berlin, November 20, 2015.

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

U. Bandelow, Multidimensional modeling and simulation of electrically pumped semiconductorbased emitters, Blockseminar of SFB 787 School of Nanophotonics, May 11  13, 2015, TU Berlin, GraalMüritz, 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 edgeemitting semiconductor lasers, CLEO/EuropeEQEC 2015 Conference, München, June 21  25, 2015.

M. Radziunas, V. Tronciu, E. Luvsandamdin, Ch. Kürbis, A. Wicht, H. Wenzel, Coexistence of multiple stable continuouswave states in microintegrated externalcavity diode lasers, CLEO/EuropeEQEC 2015 Conference, München, June 21  25, 2015.

M. Radziunas, Computation and analysis of longitudinal optical modes in multisection ring and edgeemitting 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 edgeemitting broadarea 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, Control of cavity solitons by timedelayed optical feedback, International Conference ``Dynamics, Bifurcations and Strange Attractors'', July 20  24, 2015, Nizhny Novgorod, Russian Federation, July 22, 2015.

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

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

R.M. Arkhipov, M. Radziunas, A.G. Vladimirov, Theoretical analysis of the influence of external periodic forcing on nonlinear dynamics of passively modelocked 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, Modelocking 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 ultrashort 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 modelocked 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 modelocked QD lasers, PROPHET Meeting, June, 2627, 2014, June 25  28, 2014, Cork, Ireland, June 27, 2014.

R.M. Arkhipov, Pulse repetitionfrequency multiplication of passively modelocked 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 modelocking 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 modelocked 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(1x)Asbased distributed Bragg reflectors, International NanoOptoelecteonics Workshop (iNOW 2014), St. Petersburg, Russian Federation, August 9  23, 2014.

A. Pimenov, Robust homocline in a predatorprey system with hysteresis, International Multidisciplinary Workshop MURPHYSHSFS2014, WIAS Berlin, April 9, 2014.

A. Pimenov, The effect of noise on timing jitter in a modelocked semiconductor laser, International Workshop "Nonlinear Dynamics in Semiconductor Lasers (NDSL14)", May 1214, 2014, WIAS Berlin, May 12, 2014.

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

A. Pimenov, Theoretical analysis of passively modelocked 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 edgeemitting 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 EUROPAR' 2014'', August 25  26, 2014, Porto, Portugal, August 25, 2014.

M. Radziunas, Longitudinal mode analysis of multisection ring and edgeemitting 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 LDSLtool, 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 edgeemitting semiconductor devices, Conference SPIE Photonics Europe, April 1417, 2014, April 14  17, 2014, Brussels, Belgium, April 15, 2014.

M. Radziunas, Simulations and analysis of beam shaping in spatially modulated broad area edgeemitting 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 NLStype 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 NanoOptoelectronics 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 selfcompression in the high harmonic spectrum from a filament, HighIntensity Lasers and HighField Phenomena (HILAS), Berlin, March 18  20, 2014.

C. Brée, Manipulating optical solitons with a groupvelocity 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 modelocked lasers and passive fiber cavities, Conference SPIE Photonics Europe, April 1417, 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 SakaguchiKuramoto model, International Conference on Control of Selforganizing Nonlinear Systems, RostockWarnemünde, 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, Delaydifferential 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 modelocked 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 modelocked lasers, 2013 International NanoOptoelectronics 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 modelocked semiconductor lasers with external periodic forcing, 4th GRISC 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 GRISC 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. PérezSerrano, 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. PérezSerrano, Emission wavelength multistability in semiconductor ring lasers, CLEO/EUROPE  IQEC 2013, München, May 12  16, 2013.

A. PérezSerrano, Multichannel wavelength conversion using fourwave 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 twosection passively modelocked 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 delaydifferential 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 predatorprey and SIR systems, Equadiff13, MS20  Slowfast 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 edgeemitting broadarea semiconductor devices, Parallel Processing and Applied Mathematics (PPAM 2013), September 8  11, 2013, Warsaw, Poland, September 11, 2013.

M. Radziunas, Nonlinear dynamics in modelocked lasers: Modeling, simulations and analysis, 2013 International NanoOptoelectronics 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 edgeemitting 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 NanoOptoelectronics Workshop (iNOW'2013), August 19  30, 2013, Cargèse, France, August 26, 2013.

U. Bandelow, Heteroclinic connections and limiting cases in integrable NLStype 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 SasaSatsuma 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 modelocked 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 twolevel optically dense medium, International Conference ``Laser Optics 2012'', St. Petersburg, Russian Federation, June 25  29, 2012.

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

R. Arkhipov, Modelling of modelocked 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 modelocking in edgeemitting 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 AllRussian Scientific SchoolSeminar ``Wave Phenomena in Inhomogeneous Media'' (Waves2012), May 21  28, 2012, Zvenigorod, Russian Federation, May 24, 2012.

R. Arkhipov, Hybrid modelocking in semiconductor quantum dot lasers: Simulation, analysis and comparison with experiments, ITN PROPHET MidTerm Review Meeting, October 9  11, 2012, Paris, France, October 11, 2012.

R. Arkhipov, Numerical analysis of hybrid modelocking in semiconductor quantum dot lasers, XIV AllRussian Scientific SchoolSeminar ``Wave Phenomena in Inhomogeneous Media'' (Waves2012), 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 alloptical streak camera based on ultrafast laser beam deflection by lightinduced 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 modelocking in twosection semiconductor quantum dot lasers, International Symposium Advances in Nonlinear Photonics, September 23  27, 2012, Belarusian State University, Minsk, Belarus, September 24, 2012.

A. PérezSerrano, 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 multistripe laser array with external offaxis feedback, SPIE Photonics Europe 2012 Conference, April 16  19, 2012, Brussels, Belgium, April 17, 2012.

M. Radziunas, Hybrid modelocking 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, GraalMüritz, May 15, 2012.

U. Bandelow, Rogue waves in extended nonlinear Schrödinger equations: Integrable SasaSatsuma 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 SasaSatsuma equation, International Symposium ``Advances in Nonlinear Photonics'', September 24  28, 2012, Belarusian State University, Minsk, September 25, 2012.

U. Bandelow, Spatiotemporal 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 SakaguchiKuramoto model, Colloquium on Complex and Biological Systems, Universität Potsdam, November 26, 2012.

O. Omel'chenko, Partially synchronized patterns in systems of nonlocally 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 modelocked 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, FritzHaberInstitut, Berlin, June 15, 2012.

M. Radziunas, Broadening of modelocking pulses in quantumdot 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/EuropeEQEC Conference, 2226 May 2011, München, May 26, 2011.

A.G. Vladimirov, Modelocking 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/EuropeEQEC Conference, 2226 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 threedimensional reservoirs to quantum dot states, 11th International Conference on Physics of LightMatter 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 NanoOptoelectronic Systems, February 4  5, 2011, WIAS, February 4, 2011.

M. Radziunas, Drittmittelaquise  Wie schreibe ich einen Drittmittelantrag ?, Weiterbildungsveranstaltung SW 014SS 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/EuropeEQEC Conference, 2226 May 2011, München, May 25, 2011.

M. Radziunas, Strong asymmetry of modelocking pulses in quantumdot semiconductor lasers, CLEO/EuropeEQEC Conference, 2226 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 modelocked 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 AllOptical Kerr Effect, CLEO/EuropeEQEC Conference, 2226 May 2011, München, May 26, 2011.

V. Tronciu, High power lasers for modern technologies, NANO2011 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 quantumdot modelocked 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 multisection semiconductor laser, École Polytechnique Fédérale de Lausanne (EPFLSB), 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 modelocking 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, GraalMüritz, May 10, 2010.

A.G. Vladimirov, Locking characteristics of a 40 GHz hybrid modelocked 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 nonlocally coupled Kuramototype models, Universität Potsdam, Institut für Physik und Astronomie, October 25, 2010.

T. Girnyk, Multistability of twisted states in nonlocally coupled Kuramototype models, École Polytechnique Fédérale de Lausanne, Laboratory of Nonlinear Systems (EPFLLANOS), 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, MathematischNaturwissenschaftliche Fakultät, Institut für Physik und Astronomie, Arbeitsgruppe Photonik, Berlin, February 24, 2010.

M. Radziunas, Theoretical investigations of the pulse broadening in modelocked quantumdot 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 HalbleiterNanophotonik, Technische Universität Berlin, April 23, 2010.

M. Radziunas, LDSLtool: a software for simulation and analysis of Longitudinal Dynamics in Semiconductor Lasers, FerdinandBraunInstitut für Höchstfrequenztechnik, Berlin, January 6, 2009.

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

M. Radziunas, Numerical bifurcation analysis for multisection 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 ElectroOptics 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 modelocked 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 modelocked quantum dot semiconductor lasers, European Conference on Lasers and ElectroOptics and the XIth European Quantum Electronics 2009 Conference (CLEO®/EuropeEQEC), 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 distributedfeedback tapered masteroscillator poweramplifiers, European Conference on Lasers and ElectroOptics and the XIth European Quantum Electronics Conference 2009 (CLEOtextsuperscript®/Europe  EQEC 2009), Munich, June 14  19, 2009.

V.Z. Tronciu, Chaos based communication using multisection 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 masteroscillator poweramplifiers, 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 masteroscillator poweramplifiers. 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 DFBMOPA and DBR tapered poweramplifiers, Photo Meeting, University of the Balearic Islands, Institute for CrossDisciplinary Physics and Complex Systems (IFISC), Palma de Mallorca, Spain, June 26, 2009.

V.Z. Tronciu, Numerical simulations of DFBMOPA and DBR tapered poweramplifiers, Universidad Politécnica de Madrid, Departamento de Tecnología Fotónica, Spain, June 29, 2009.

A.G. Vladimirov, Hybrid modelocking in a 40 GHz monolithic quantum dot laser, European Conference on Lasers and ElectroOptics and the XIth European Quantum Electronics 2009 Conference (CLEO®/EuropeEQEC), 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 QDgain, International NanoOptoelectronic Workshop (iNOW 2009), Stockholm, Sweden, and Berlin, Germany, August 2  15, 2009.

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

U. Bandelow, 3D semiclassical multispecies modeling of QD lasers, International NanoOptoelectronic 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 distributedfeedback tapered masteroscillator poweramplifiers, 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 modelocked quantum dot laser, SPIE Photonics Europe Conference, April 7  10, 2008, Strasbourg, France, April 8, 2008.

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

A.G. Vladimirov, Modelocking 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 masteroscillator poweramplifier 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, GraalMüritz, May 23, 2008.

U. Bandelow, Quantumclassical 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 StateoftheArt 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 singlemode DFB laser with integrated passive feedback section for direct modulation applications, European Conference on Lasers and ElectroOptics, 2007/International Quantum Electronics Conference (CLEOIQEC 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, FraunhoferInstitut für Nachrichtentechnik, HeinrichHertzInstitut, 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, HeinrichHertzInstitut, 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, HumboldtUniversität 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 modelocked semiconductor laser, Workshop on Nonlinear Dynamics in Semiconductor Lasers, November 19  21, 2007, WIAS, Berlin, November 21, 2007.

A.G. Vladimirov, Passive modelocking 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 LDSLtool: Simulation and analysis of dynamics in semiconductor lasers, LaserOptikBerlin, March 23  24, 2006.

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

M. Radziunas, External cavity modes in LangKobayashi 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 LDSLtool, WIASDay, 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, HumboldtUniversität zu Berlin, September 12, 2006.

M. Radziunas, Traveling wave modeling of modelocking 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, Kickoff Workshop ``Materials in New Light'', HumboldtUniversität zu Berlin, Institut für Physik, Berlin, January 6, 2006.

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

U. Bandelow, Modellierung und Simulation von Pulsquellen, Status Seminar TerabitOptics Berlin, HeinrichHertzInstitut für Nachrichtentechnik, Berlin, July 4, 2006.

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

U. Bandelow, Simulation and analysis of spatiotemporal effects in complex laser structures, Kickoff Workshop ``Materials in New Light'', HumboldtUniversität zu Berlin, Institut für Physik, Berlin, January 6, 2006.

A. Glitzky, R. Nürnberg, U. Bandelow, ttfamily WIASTeSCA: Simulation of semiconductor lasers, LaserOptikBerlin, 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 modelocked 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, Travelingwave modeling of semiconductor lasers and amplifiers, 5th International Conference ``Numerical Simulation of Optoelectronic Devices'' (NUSOD 05), September 19  22, 2005, HumboldtUniversität, 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 Highdimensional 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, HumboldtUniversität, Berlin, September 20, 2005.

M. Radziunas, Tailoring the dynamics of multisection lasers for 40 Gb/s direct modulation, Evaluation of DIMOLAProject, FraunhoferInstitut für Nachrichtentechnik, HeinrichHertzInstitut, 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 modelocking 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, WIASDay, Berlin, February 23, 2005.

A. Vladimirov, Theoretical analysis of dynamical instabilities in a modelocked 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 LangKobayashi 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 modelocking, International Quantum Electronics Conference, München, June 12  17, 2005.

U. Bandelow, Analyse dynamischer Effekte in Optoelektronik und Photonik, Institutsseminar, FerdinandBraunInstitut für Höchstfrequenztechnik, Berlin, December 9, 2005.

U. Bandelow, Modellierung und Simulation von Pulsquellen, Status Seminar of the TerabitOpticsBerlin Project, Fraunhofer Institut für Nachrichtentechnik, HeinrichHertzInstitut, Berlin, May 31, 2005.

U. Bandelow, Reduced amplitude noise in monolithic modelocked 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 Highdimensional Chaos in Coupled Systems'', November 15  16, 2004, Berlin, November 16, 2004.

M. Radziunas, Simulation and analysis of 40 GHz monolithic modelocked 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 Highdimensional Chaos in Coupled Systems'', November 15  16, 2004, Berlin, November 15, 2004.

U. Bandelow, M. Radziunas, Time domain simulation of 40 GHz modelocked semiconductor lasers, WIAS MiniSymposium on Modelocked Semiconductor Lasers, March 22  23, 2004, Berlin, March 22, 2004.

U. Bandelow, 40 GHz modelocked 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 modelocked 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 TerabitOpticsBerlin Project, Technische Universität Berlin, May 3, 2004.

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

U. Bandelow, Timedomain modeling of psOEIC, 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 modelocked laser, EPSQEOD 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, DDEbased modelling of passively modelocked 40 GHz semiconductor lasers, WIAS MiniSymposium on Modelocked Semiconductor Lasers, March 22  23, 2004, Berlin, March 22, 2004.

U. Bandelow, M. Radziunas, Simulation of modelocked lasers with LDSLtool, European Quantum Electronics Conference (EQEC 2003), June 23  27, 2003, München, June 26, 2003.

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

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

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

U. Bandelow, Simulation of modelocked lasers based on a distributed timedomain 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 pathfollowing 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 multisection 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/EuropeEQEC 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, MathInsideÜberall 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 modelocking, WIAS Workshop ``Dynamics of Semiconductor Lasers'', September 15  17, 2003, Berlin, September 17, 2003.

A.G. Vladimirov, Passive modelocking 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 LangKobayashi systems, National Institute of Applied Optics, Florence, Italy, May 7, 2003.

S. Yanchuk, Synchronization problem in twosection semiconductor lasers, Forschungsseminar ``Angewandte Analysis'', HumboldtUniversität 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 multisection 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 (NUSOD02), September 25  27, 2002, Eidgenössische Technische Hochschule Zürich, Switzerland, September 25, 2002.

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

M. Radziunas, Simulation and analysis of dynamics in multisection semiconductor DFB laser, First SIAMEMS 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'', HumboldtUniversität 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.
External Preprints

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 laminarturbulent 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. SchulzRuhtenberg, I. Babushkin, N.A. Loiko, K.F. Huang, T. Ackemann, Polarization properties in the transition from below to above lasing threshold in broadarea verticalcavity surfaceemitting lasers (electronic only), Preprint no. arXiv:0909.3812, Cornell University Library, arXiv.org, 2009.
Abstract
For highly divergent emission of broadarea verticalcavity surfaceemitting 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, nearthreshold and abovethreshold 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, Scarlike structures and nonintegrability in a perfectly square optical billiard (electronic only), Preprint no. arXiv:0909.4330, Cornell University Library, arXiv.org, 2009.
Abstract
We show that scarlike 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.