Publications

Monographs

  • P. Farrell, N. Rotundo, D.H. Doan, M. Kantner, J. Fuhrmann, Th. Koprucki, Chapter 50: Drift-Diffusion Models, 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. 733--771, (Chapter Published).

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

Articles in Refereed Journals

  • I. Omelchenko, O.E. Omel'chenko, A. Zakharova, E. Schöll, Optimal design of the tweezer control for chimera states, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 97 (2018), published online on 25.01.2018, DOI https://doi.org/10.1103/PhysRevE.97.012216 .
    Abstract
    Chimera states are complex spatio-temporal patterns, which consist of coexisting domains of spatially coherent and incoherent dynamics in systems of coupled oscillators. In small networks, chimera states usually exhibit short lifetimes and erratic drifting of the spatial position of the incoherent domain. A tweezer feedback control scheme can stabilize and fix the position of chimera states. We analyse the action of the tweezer control in small nonlocally coupled networks of Van der Pol and FitzHugh--Nagumo oscillators, and determine the ranges of optimal control parameters. We demonstrate that the tweezer control scheme allows for stabilization of chimera states with different shapes, and can be used as an instrument for controlling the coherent domains size, as well as the maximum average frequency difference of the oscillators.

  • O. Burylko, A. Mielke, M. Wolfrum, S. Yanchuk, Coexistence of Hamiltonian-like and dissipative dynamics in chains of coupled phase oscillators with skew-symmetric coupling, SIAM Journal on Applied Dynamical Systems, 17 (2018), pp. 2076--2105, DOI 10.1137/17M1155685 .
    Abstract
    We consider rings of coupled phase oscillators with anisotropic coupling. When the coupling is skew-symmetric, i. e. when the anisotropy is balanced in a specific way, the system shows robustly a coexistence of Hamiltonian-like and dissipative regions in the phase space. We relate this phenomenon to the time-reversibility property of the system. The geometry of low-dimensional systems up to five oscillators is described in detail. In particular, we show that the boundary between the dissipative and Hamiltonian-like regions consists of families of heteroclinic connections. For larger chains with skew-symmetric coupling, some sufficient conditions for the coexistence are provided, and in the limit of N → ∞ oscillators, we formally derive an amplitude equation for solutions in the neighborhood of the synchronous solution. It has the form of a nonlinear Schrödinger equation and describes the Hamiltonian-like region existing around the synchronous state similarly to the case of finite rings.

  • O.O. Omel'chenko, M. Wolfrum, E. Knobloch, Stability of spiral chimera states on a torus, SIAM Journal on Applied Dynamical Systems, 17 (2018), pp. 97--127, DOI 10.1137/17M1141151 .
    Abstract
    We study destabilization mechanisms of spiral coherence-incoherence patterns known as spiral chimera states that form on a two-dimensional lattice of nonlocally coupled phase oscillators. For this purpose we employ the linearization of the Ott--Antonsen equation that is valid in the continuum limit and perform a detailed two-parameter stability analysis of a $D_4$-symmetric chimera state, i.e., a four-core spiral state. We identify fold, Hopf and parity-breaking bifurcations as the main mechanisms whereby spiral chimeras can lose stability. Beyond these bifurcations we find new spatio-temporal patterns, in particular, quasiperiodic chimeras, $D_2$-symmetric spiral chimeras as well as drifting states.

  • U. Bandelow, A. Ankiewicz, S. Amiranashvili, N. Akhmediev, Sasa--Satsuma hierarchy of integrable evolution equations, Chaos. An Interdisciplinary Journal of Nonlinear Science, (2018), published online on 17.05.2018, DOI 10.1063/1.5030604 .
    Abstract
    We present the infinite hierarchy of Sasa-Satsuma evolution equations. The corresponding Lax pairs are given, thus proving its integrability. The lowest order member of this hierarchy is the nonlinear Schrödinger equation, while the next one is the Sasa-Satsuma equation that includes third-order terms. Up to sixth- order terms of the hierarchy are given in explicit form, while the provided recurrence relation allows one to explicitly write all higher-order terms. The whole hierarchy can be combined into a single general equation. Each term in this equation contains a real independent coefficient that provides the possibility of adapting the equation to practical needs. A few examples of exact solutions of this general equation with an infinite number of terms are also given explicitly.

  • O.E. Omel'chenko, The mathematics behind chimera states, Nonlinearity, 31 (2018), published online on 04.04.2018, DOI https://doi.org/10.1088/1361-6544/aaaa07 .
    Abstract
    Chimera states are self-organized spatiotemporal patterns of coexisting coherence and incoherence. We give an overview of the main mathematical methods used in studies of chimera states, focusing on chimera states in spatially extended coupled oscillator systems. We discuss the continuum limit approach to these states, Ott--Antonsen manifold reduction, finite size chimera states, control of chimera states and the influence of system design on the type of chimera state that is observed.

  • C. Brée, M. Hofmann, I. Babushkin, A. Demircan, U. Morgner, O.G. Kosareva, A.B. Savel'ev, A. Husakou, M. Ivanov, Symmetry breaking and strong persistent plasma currents via resonant destabilization of atoms, Physical Review Letters, 119 (2017), pp. 243202/1--243202/5.
    Abstract
    The ionization rate of an atom in a strong optical field can be resonantly enhanced by the presence of long-living atomic levels (so called Freeman resonances). This process is most prominent in the multiphoton ionization regime meaning that ionization event takes many optical cycles. Nevertheless, here we show that these resonances can lead to fast subcycle-scale plasma buildup at the resonant values of the intensity in the pump pulse. The fast buildup can break the cycle-to-cycle symmetry of the ionization process, resulting in generation of persistent macroscopic plasma currents which remain after the end of the pulse. This, in turn, gibes rise to a broad-band radiation of unusual spectral structure forming a comb from terahertz (THz) to visible. This radiation contains fingerprints of the attosecond electronic dynamics in Rydberg states during ionization.

  • C. Brée, I. Babushkin, U. Morgner, A. Demircan, Regularizing aperiodic cycles of resonant radiation in filament light bullets, Physical Review Letters, 118 (2017), pp. 163901/1--163901/5, DOI 10.1103/PhysRevLett.118.163901 .
    Abstract
    We demonstrate an up to now unrecognized and very effective mechanism which prevents filament collapse and allows persistent self-guiding propagation retaining larg portion of the optical energy on-axis over unexpected long distances. The key ingredient is the possibility of leaking continuously energy into the normal dispersion regime via emission of resonant radiation. The frequency of the radiation is determined by the dispersion dynamically modified by photo-generated plasma, thus allowing to excite new frequencies in the spectral ranges which are otherwise difficult to access.

  • S. Eydam, M. Wolfrum, Mode locking in systems of globally coupled phase oscillators, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 96 (2017), pp. 052205/1--052205/8, DOI 10.1103/PhysRevE.96.052205 .
    Abstract
    We investigate the dynamics of a Kuramoto-type system of globally coupled phase oscillators with equidistant natural frequencies and a coupling strength below the synchronization threshold. It turns out that in such cases one can observe a stable regime of sharp pulses in the mean field amplitude with a pulsation frequency given by spacing of the natural frequencies. This resembles a process known as mode-locking in laser and relies on the emergence of a phase relation induced by the nonlinear coupling. We discuss the role of the first and second harmonic in the phase-interaction function for the stability of the pulsations and present various bifurcating dynamical regimes such as periodically and chaotically modulated mode-locking, transitions to phase turbulence and intermittency. Moreover, we study the role of the system size and show that in certain cases one can observe type-II supertransients, where the system reaches the globally stable mode-locking solution only after an exponentially long transient of phase turbulence.

  • M. Kantner, M. Mittnenzweig, Th. Koprucki, Hybrid quantum-classical modeling of quantum dot devices, Phys. Rev. B., 96 (2017), pp. 205301/1--205301/17, DOI 10.1103/PhysRevB.96.205301 .
    Abstract
    The design of electrically driven quantum dot devices for quantum optical applications asks for modeling approaches combining classical device physics with quantum mechanics. We connect the well-established fields of semi-classical semiconductor transport theory and the theory of open quantum systems to meet this requirement. By coupling the van Roosbroeck system with a quantum master equation in Lindblad form, we obtain a new hybrid quantum-classical modeling approach, which enables a comprehensive description of quantum dot devices on multiple scales: It allows the calculation of quantum optical figures of merit and the spatially resolved simulation of the current flow in realistic semiconductor device geometries in a unified way. We construct the interface between both theories in such a way, that the resulting hybrid system obeys the fundamental axioms of (non-)equilibrium thermodynamics. We show that our approach guarantees the conservation of charge, consistency with the thermodynamic equilibrium and the second law of thermodynamics. The feasibility of the approach is demonstrated by numerical simulations of an electrically driven single-photon source based on a single quantum dot in the stationary and transient operation regime.

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

  • S. Olmi, D. Angulo-Garcia, A. Imparato, A. Torcini, Exact firing time statistics of neurons driven by discrete inhibitory noise, Scientific Reports, 7 (2017), pp. 1577/1--1577/15, DOI 10.1038/s41598-017-01658-8 .
    Abstract
    Neurons in the intact brain receive a continuous and irregular synaptic bombardment from excitatory and inhibitory pre-synaptic neurons, which determines the firing activity of the stimulated neuron. In order to investigate the influence of inhibitory stimulation on the firing time statistics, we consider Leaky Integrate-and-Fire neurons subject to inhibitory instantaneous post-synaptic potentials. In particular, we report exact results for the firing rate, the coefficient of variation and the spike train spectrum for various synaptic weight distributions. Our results are not limited to stimulations of infinitesimal amplitude, but they apply as well to finite amplitude post-synaptic potentials, thus being able to capture the effect of rare and large spikes. The developed methods are able to reproduce also the average firing properties of heterogeneous neuronal populations.

  • G. Slavcheva, M.V. Koleva, A. Pimenov, The impact of microcavity wire width on polariton soliton existence and multistability, Journal of Optics, 19 (2017), pp. 065404/1--065404/15.
    Abstract
    We have developed a model of the nonlinear polariton dynamics in realistic 3D non-planar microcavity wires in the driven-dissipative regime [15]. We find that the typical microcavity optical bistability evolves into multi-stability upon variation of the model parameters. The origin of the multi-stability is discussed in detail. We apply linear perturbation analysis to modulational instabilities, and identify conditions for localisation of composite multi-mode polariton solitons in the triggered parametric oscillator regime. Further, we demonstrate stable polariton soliton propagation in tilted and tapered waveguides, and determine maximum tilt angles for which solitons are still found. Additionally, we study soliton amplitude and velocity dependence on the wire width, with a view towards device applications.

  • D. Angulo-Garcia, S. Luccioli, S. Olmi, A. Torcini, Death and rebirth of neural activity in sparse inhibitory networks, New Journal of Physics, 19 (2017), pp. 053011/1--053011/22, DOI 10.1088/1367-2630/aa69ff .
    Abstract
    Inhibition is a key aspect of neural dynamics playing a fundamental role for the emergence of neural rhythms and the implementation of various information coding strategies. Inhibitory populations are present in several brain structures and the comprehension of their dynamics is strategical for the understanding of neural processing. In this paper, we discuss a general mechanism present in pulse-coupled heterogeneous inhibitory networks: inhibition can induce not only suppression of the neural activity, as expected, but it can also promote neural reactivation. In particular, for globally coupled systems, the number of firing neurons monotonically reduces upon increasing the strength of inhibition (neurons? death). The introduction of a sparse connectivity in the network is able to reverse the action of inhibition, i.e. a sufficiently strong synaptic strength can surprisingly promote, rather than depress, the activity of the neurons (neurons? rebirth). Specifically, for small synaptic strengths, one observes an asynchronous activity of nearly independent supra-threshold neurons. By increasing the inhibition, a transition occurs towards a regime where the neurons are all effectively sub-threshold and their irregular firing is driven by current fluctuations. We explain this transition from a mean-driven to a fluctuation-driven regime by deriving an analytic mean field approach able to provide the fraction of active neurons together with the first two moments of the firing time distribution. We show that, by varying the synaptic time scale, the mechanism underlying the reported phenomenon remains unchanged. However, for sufficiently slow synapses the effect becomes dramatic. For small synaptic coupling the fraction of active neurons is frozen over long times and their firing activity is perfectly regular. For larger inhibition the active neurons display an irregular bursting behaviour induced by the emergence of correlations in the current fluctuations. In this latter regime the model gives predictions consistent with experimental findings for a specific class of neurons, namely the medium spiny neurons in the striatum.

  • TH. Erneux, J. Javaloyes, M. Wolfrum, S. Yanchuk, Introduction to focus issue: Time-delay dynamics, Chaos. An Interdisciplinary Journal of Nonlinear Science, 27 (2017), pp. 114201/1--114201/5, DOI 10.1063/1.5011354 .
    Abstract
    The field of dynamical systems with time delay is an active research area that connects practically all scientific disciplines including mathematics, physics, engineering, biology, neuroscience, physiology, economics, and many others. This Focus Issue brings together contributions from both experimental and theoretical groups and emphasizes a large variety of applications. In particular, lasers and optoelectronic oscillators subject to time-delayed feedbacks have been explored by several authors for their specific dynamical output, but also because they are ideal test-beds for experimental studies of delay induced phenomena. Topics include the control of cavity solitons, as light spots in spatially extended systems, new devices for chaos communication or random number generation, higher order locking phenomena between delay and laser oscillation period, and systematic bifurcation studies of mode-locked laser systems. Moreover, two original theoretical approaches are explored for the so-called Low Frequency Fluctuations, a particular chaotical regime in laser output which has attracted a lot of interest for more than 30?years. Current hot problems such as the synchronization properties of networks of delay-coupled units, novel stabilization techniques, and the large delay limit of a delay differential equation are also addressed in this special issue. In addition, analytical and numerical tools for bifurcation problems with or without noise and two reviews on concrete questions are proposed. The first review deals with the rich dynamics of simple delay climate models for El Nino Southern Oscillations, and the second review concentrates on neuromorphic photonic circuits where optical elements are used to emulate spiking neurons. Finally, two interesting biological problems are considered in this Focus Issue, namely, multi-strain epidemic models and the interaction of glucose and insulin for more effective treatment.

  • V. Klinshov, D. Shchapin, S. Yanchuk, M. Wolfrum, O. D'huys, V. Nekorkin, Embedding the dynamics of a single delay system into a feed-forward ring, Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, 96 (2017), pp. 042217/1--042217/9.
    Abstract
    We investigate the relation between the dynamics of a single oscillator with delayed self-feedback and a feed-forward ring of such oscillators, where each unit is coupled to its next neighbor in the same way as in the self-feedback case. We show that periodic solutions of the delayed oscillator give rise to families of rotating waves with different wave numbers in the corresponding ring. In particular, if for the single oscillator the periodic solution is resonant to the delay, it can be embedded into a ring with instantaneous couplings. We discover several cases where stability of periodic solution for the single unit can be related to the stability of the corresponding rotating wave in the ring. As a specific example we demonstrate how the complex bifurcation scenario of simultaneously emerging multi-jittering solutions can be transferred from a single oscillator with delayed pulse feedback to multi-jittering rotating waves in a sufficiently large ring of oscillators with instantaneous pulse coupling. Finally, we present an experimental realization of this dynamical phenomenon in a system of coupled electronic circuits of FitzHugh-Nagumo type.

  • D. Puzyrev, A.G. Vladimirov, A. Pimenov, S.V. Gurevich, S. Yanchuk, Bound pulse trains in arrays of coupled spatially extended dynamical systems, Physical Review Letters, 119 (2017), pp. 163901/1--163901/6, DOI 10.1103/PhysRevLett.119.163901 .
    Abstract
    We study the dynamics of an array of nearest-neighbor coupled spatially distributed systems each generating a periodic sequence of short pulses. We demonstrate that, unlike a solitary system generating a train of equidistant pulses, an array of such systems can produce a sequence of clusters of closely packed pulses, with the distance between individual pulses depending on the coupling phase. This regime associated with the formation of locally coupled pulse trains bounded due to a balance of attraction and repulsion between them is different from the pulse bound states reported earlier in different laser, plasma, chemical, and biological systems. We propose a simplified analytical description of the observed phenomenon, which is in good agreement with the results of direct numerical simulations of a model system describing an array of coupled mode-locked lasers.

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

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

  • A.P. Willis, Y. Duguet, O. Omel'chenko, M. Wolfrum, Surfing the edge: Finding nonlinear solutions using feedback control, Journal of Fluid Mechanics, 831 (2017), pp. 579--591.
    Abstract
    Many transitional wall-bounded shear flows are characterised by the coexistence in state-space of laminar and turbulent regimes. Probing the edge boundarz between the two attractors has led in the last decade to the numerical discovery of new (unstable) solutions to the incompressible Navier--Stokes equations. However, the iterative bisection method used to achieve this can become prohibitively costly for large systems. Here we suggest a simple feedback control strategy to stabilise edge states, hence accelerating their numerical identification by several orders of magnitude. The method is illustrated for several configurations of cylindrical pipe flow. Traveling waves solutions are identified as edge states, and can be isolated rapidly in only one short numerical run. A new branch of solutions is also identified. When the edge state is a periodic orbit or chaotic state, the feedback control does not converge precisely to solutions of the uncontrolled system, but nevertheless brings the dynamics very close to the original edge manifold in a single run. We discuss the opportunities offered by the speed and simplicity of this new method to probe the structure of both state space and parameter space.

  • I. Babushkin, C. Brée, Ch.M. Dietrich, A. Demircan, U. Morgner, A. Husakou, Terahertz and higher-order Brunel harmonics: From tunnel to multiphoton ionization regime in tailored fields, Journal of Modern Optics, 67 (2017), pp. 1078--1087, DOI 10.1080/09500340.2017.1285066 .
    Abstract
    Brunel radiation appears as a result of a two-step process of photo-ionization and subsequent acceleration of electron, without the need of electron recollision. We show that for generation of Brunel harmonics at all frequencies, the subcycle ionization dynamics is of critical importance. Namely, such harmonics disappear at the low pump intensities when the ionization dynamics depends only on the slow envelope (so-called multiphoton ionization regime) and not on the instantaneous field. Nevertheless, if the pump pulse contains incommensurate frequencies, Brunel mechanism does generate new frequencies even in the multiphoton ionization regime.

  • N. Raabe, T. Feng, T. Witting, A. Demircan, C. Brée, G. Steinmeyer, Role of intrapulse coherence in carrier-envelope phase stabilization, Physical Review Letters, 119 (2017), pp. 123901/1--123901/5, DOI 10.1103/PhysRevLett.119.123901 .
    Abstract
    The concept of coherence is of fundamental importance for describing the physical characteristics of light and for evaluating the suitability for experimental application. In the case of pulsed laser sources, the pulse-to-pulse coherence is usually considered for a judgment of the compressibility of the pulse train. This type of coherence is often lost during propagation through a highly nonlinear medium, and pulses prove incompressible despite multioctave spectral coverage. Notwithstanding the apparent loss of interpulse coherence, however, supercontinua enable applications in precision frequency metrology that rely on coherence between different spectral components within a laser pulse. To judge the suitability of a light source for the latter application, we define an alternative criterion, which we term intrapulse coherence. This definition plays a limiting role in the carrier-envelope phase measurement and stabilization of ultrashort pulses. It is shown by numerical simulation and further corroborated by experimental data that filamentation-based supercontinuum generation may lead to a loss of intrapulse coherence despite near-perfect compressibility of the pulse train. This loss of coherence may severely limit active and passive carrier-envelope phase stabilization schemes and applications in optical high-field physics.

  • S. Pickartz, C. Brée, U. Bandelow, S. Amiranashvili, Cancellation of Raman self-frequency shift for compression of optical pulses, Optical and Quantum Electronics, 49 (2017), pp. 328/1--328/7, DOI 10.1007/s11082-017-1164-7 .
    Abstract
    We study to which extent a fiber soliton can be manipulated by a specially chosen continuous pump wave. A group velocity matched pump scatters at the soliton, which is compressed due to the energy/momentum transfer. As the pump scattering is very sensitive to the velocity matching condition, soliton compression is quickly destroyed by the soliton self-frequency shift (SSFS). This is especially true for ultrashort pulses: SSFS inevitably impairs the degree of compression. We demonstrate numerically that soliton enhancement can be restored to some extent and the compressed soliton can be stabilized, provided that SSFS is canceled by a second pump wave. Still the available compression degree is considerably smaller than that in the Raman-free nonlinear fibers.

  • S. Pickartz, U. Bandelow, S. Amiranashvili, Asymptotically stable compensation of soliton self-frequency shift, Optics Letters, 42 (2017), pp. 1416--1419, DOI 10.1364/OL.42.001416 .
    Abstract
    We report the cancellation of the soliton self-frequency shift in nonlinear optical fibers. A soliton which interacts with a group velocity matched low intensity dispersive pump pulse, experiences a continuous blue-shift in frequency, which counteracts the soliton selffrequency shift due to Raman scattering. The soliton self-frequency shift can be fully compensated by a suitably prepared dispersive wave.We quantify this kind of soliton-dispersive wave interaction by an adiabatic approach and demonstrate that the compensation is stable in agreement with numerical simulations.

  • O. Omel'chenko, L. Recke, V. Butuzov, N. Nefedov, Time-periodic boundary layer solutions to singularly perturbed parabolic problems, Journal of Differential Equations, 262 (2017), pp. 4823--4862.
    Abstract
    In this paper, we present a result of implicit function theorem type, which was designed for application to singularly perturbed problems. This result is based on fixed point iterations for contractive mappings, in particular, no monotonicity or sign preservation properties are needed. Then we apply our abstract result to time-periodic boundary layer solutions (which are allowed to be non-monotone with respect to the space variable) in semilinear parabolic problems with two independent singular perturbation parameters. We prove existence and local uniqueness of those solutions, and estimate their distance to certain approximate solutions.

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

Contributions to Collected Editions

  • M. Kantner, M. Mittnenzweig, Th. Koprucki, A hybrid quantum-classical modeling approach for electrically driven quantum dot devices, in: Proceedings of ``SPIE Photonics West 2018: Physics and Simulation of Optoelectronic Devices XXVI'', San Francisco, USA, 29.01.2018 - 01.02.2018, 10526, Society of Photo-Optical Instrumentation Engineers (SPIE), Bellingham, 2018, pp. 10526/1--10526/6, DOI 10.1117/12.2289185 .
    Abstract
    The design of electrically driven quantum light sources based on semiconductor quantum dots, such as singlephoton emitters and nanolasers, asks for modeling approaches combining classical device physics with cavity quantum electrodynamics. In particular, one has to connect the well-established fields of semi-classical semiconductor transport theory and the theory of open quantum systems. We present a first step in this direction by coupling the van Roosbroeck system with a Markovian quantum master equation in Lindblad form. The resulting hybrid quantum-classical system obeys the fundamental laws of non-equilibrium thermodynamics and provides a comprehensive description of quantum dot devices on multiple scales: It enables the calculation of quantum optical figures of merit (e.g. the second order intensity correlation function) together with the spatially resolved simulation of the current flow in realistic semiconductor device geometries in a unified way.

  • V.Z. Tronciu, H. Wenzel, M. Radziunas, M. Reggentin, J. Wiedmann, A. Knigge, Numerical and experimental studies of a distributed Bragg reflector laser, in: Proceedings of ``International Conference on Telecommunications, Electronics and Informatics (ICTEI 2018)'', Chisinau, Moldawien, 24.05.2018 - 27.05.2018, S. Andronic, I. Tighineanu, V. Tronciu, eds., 6 of Telecommunications, Electronics and Informatics, Technical University of Moldova, 2018, pp. 105--108.
    Abstract
    We report in this paper theoretical and experimental results on the dynamical properties of a distributed Bragg reflector (DBR) semiconductor lasers. Using the traveling wave equation model, we show that a proper choice of coupling coefficient and front facet reflectivity allows an optimization of the laser operation, such that for a wide range of currents injected into the active region the laser emits a continuous-wave beam. The numerical results are in a qualitative agreement with measured characteristics.

  • M. Wolfrum, Enumeration of positive meanders, in: Proceedings of ``International Conference on Patterns of Dynamics'', P. Gurevich, J. Hell, B. Sandstede, A. Scheel, eds., 205 of Springer Proceedings in Mathematics & Statistics, Springer, Cham, 2018, pp. 203--212, DOI 10.1007/978-3-319-64173-7_13 .
    Abstract
    Meanders are geometrical objects, defined by a non-self-intersecting curve, intersecting several times through an infinite straight line. The subclass of positive meanders has been defined and used extensively for the study of the attractors of scalar parabolic PDEs. In this paper, we use bracket sequences and winding numbers to investigate the class of positive meanders. We prove a theorem about possible combinations of bracket sequences to obtain a meander with prescribed winding numbers and present an algorithm to compute the number of positive meanders with a given number of intersection points.

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

  • G. Slavcheva, M.V. Koleva, A. Pimenov, Simulation of nonlinear polariton dynamics in microcavity wires for polaritonic integrated circuits, 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. 187--188, DOI 10.1109/NUSOD.2017.8010054 .

  • D. Puzyrev, A.G. Vladimirov, A. Pimenov, S.V. Gurevich, S. Yanchuk, Pulse bound-state clusters in coupled mode-locked lasers, in: Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) 2017 Conference on, IEEE, New York, 2017, DOI 10.1109/CLEOE-EQEC.2017.8087527 .
    Abstract
    Mode-locked semiconductor lasers are widely used for generation of short optical pulses with high repetition rates and optical frequency combs suitable for numerous practical applications. By combining many lasers into an array one can achieve much larger output power and substantially improve the characteristics of the output radiation. In this presentation we study dynamical regimes of operation in an array of mode-locked lasers locally coupled in a ring geometry. We demonstrate that unlike a solitary mode-locked laser emitting a sequence of equidistant pulses with the pulse repetition frequency close to the inverse cavity round trip time, an array of mode-locked lasers can radiate a periodic sequence of clusters of fundamental mode-locked pulses. This regime associated with the formation of closely packed bound states of coupled mode-locked pulses due to a balance between attraction and repulsion is very different from the standard harmonic mode-locked regime where the pulses always repel each other.

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

  • S. Pickartz, C. Brée, U. Bandelow, S. Amiranashvili, Cancellation of Raman self-frequency shift for compression of optical pulses, in: Proceedings of the 17th International Conference on Numerical Simulation of Optoelectronic Devices -- NUSOD 2017, J. Piprek, M. Piprek, eds., IEEE Conference Publications Management Group, Piscataway, 2017, pp. 173--174.

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

Preprints, Reports, Technical Reports

  • N. Akhmediev, A. Ankiewicz, S. Amiranashvili, U. Bandelow, Generalized integrable evolution equations with an infinite number of free parameters, Preprint no. 2529, WIAS, Berlin, 2018, DOI 10.20347/WIAS.PREPRINT.2529 .
    Abstract, PDF (1005 kByte)
    Evolution equations such as the nonliear Schrödinger equation (NLSE) can be extended to include an infinite number of free parameters. The extensions are not unique. We give two examples that contain the NLSE as the lowest-order PDE of each set. Such representations provide the advantage of modelling a larger variety of physical problems due to the presence of an infinite number of higher-order terms in this equation with an infinite number of arbitrary parameters. An example of a rogue wave solution for one of these cases is presented, demonstrating the power of the technique.

  • I. Bačić, S. Yanchuk, M. Wolfrum, I. Franović, Noise-induced switching in two adaptively coupled excitable systems, Preprint no. 2517, WIAS, Berlin, 2018, DOI 10.20347/WIAS.PREPRINT.2517 .
    Abstract, PDF (4570 kByte)
    We demonstrate that the interplay of noise and plasticity gives rise to slow stochastic fluctuations in a system of two adaptively coupled active rotators with excitable local dynamics. Depending on the adaptation rate, two qualitatively different types of switching behavior are observed. For slower adaptation, one finds alternation between two modes of noise-induced oscillations, whereby the modes are distinguished by the different order of spiking between the units. In case of faster adaptation, the system switches between the metastable states derived from coexisting attractors of the corresponding deterministic system, whereby the phases exhibit a bursting-like behavior. The qualitative features of the switching dynamics are analyzed within the framework of fast-slow analysis.

  • S. Eydam, I. Franović, M. Wolfrum, Leap-frog patterns in systems of two coupled FitzHugh--Nagumo units, Preprint no. 2514, WIAS, Berlin, 2018, DOI 10.20347/WIAS.PREPRINT.2514 .
    Abstract, PDF (4211 kByte)
    We study a system of two identical FitzHugh-Nagumo units with a mutual linear coupling in the fast variables. While an attractive coupling always leads to synchronous behavior, a repulsive coupling can give rise to dynamical regimes with alternating spiking order, called leap-frogging. We analyze various types of periodic and chaotic leap-frogging regimes, using numerical pathfollowing methods to investigate their emergence and stability, as well as to obtain the complex bifurcation scenario which organizes their appearance in parameter space. In particular, we show that the stability region of the simplest periodic leap-frog pattern has the shape of a locking cone pointing to the canard transition of the uncoupled system. We also discuss the role of the timescale separation in the coupled FitzHugh-Nagumo system and the relation of the leap-frog solutions to the theory of mixed-mode oscillations in multiple timescale systems.

  • S. Amiranashvili, E. Tobisch, Generalized Lighthill criterion for the modulation instability, Preprint no. 2512, WIAS, Berlin, 2018, DOI 10.20347/WIAS.PREPRINT.2512 .
    Abstract, PDF (1138 kByte)
    An universal modulation instability is subject to Lighthill criterion: nonlinearity and dispersion should make opposite contributions to the wave frequency. Recent studies of wave instabilities in optical fibers with the minimum chromatic dispersion revealed situations in which the criterion is violated and fast unstable modulations appear due to the four wave mixing process. We derive a generalized criterion, it applies to an arbitrary dispersion and to both slow and fast unstable modulations. Since the fast modulations depend on nonlinear dispersion, we also demonstrate how to describe them in the framework of a single generalized nonlinear Schrödinger equation.

  • A. Ankiewicz, U. Bandelow, N. Akhmediev, Generalized Sasa--Satsuma equation: Densities approach to new infinite hierarchy of integrable evolution equations, Preprint no. 2510, WIAS, Berlin, 2018, DOI 10.20347/WIAS.PREPRINT.2510 .
    Abstract, PDF (186 kByte)
    We derive the new infinite Sasa-Satsuma hierarchy of evolution equations using an invariant densities approach. Being significantly simpler than the Lax-pair technique, this approach does not involve ponderous 3 x 3 matrices. Moreover, it allows us to explicitly obtain operators of many orders involved in the time evolution of the Sasa-Satsuma hierarchy functionals. All these operators are parts of a generalized Sasa-Satsuma equation of infinitely high order. They enter this equation with independent arbitrary real coefficients that govern the evolution pattern of this multi-parameter dynamical system.

  • C. Brée, D. Gailevičius, V. Purlys, G.G. Werner, K. Staliunas, A. Rathsfeld, G. Schmidt, M. Radziunas, Chirped photonic crystal for spatially filtered optical feedback to a broad-area laser, Preprint no. 2502, WIAS, Berlin, 2018, DOI 10.20347/WIAS.PREPRINT.2502 .
    Abstract, PDF (384 kByte)
    We derive and analyze an efficient model for reinjection of spatially filtered optical feedback from an external resonator to a broad area, edge emitting semiconductor laser diode. Spatial filtering is achieved by a chirped photonic crystal, with variable periodicity along the optical axis and negligible resonant backscattering. The optimal chirp is obtained from a genetic algorithm, which yields solutions that are robust against perturbations. Extensive numerical simulations of the composite system with our optoelectronic solver indicate that spatially filtered reinjection enhances lower-order transversal optical modes in the laser diode and, consequently, improves the spatial beam quality.

  • A. Zeghuzi, M. Radziunas, H. Wenzel, H.-J. Wünsche, U. Bandelow, A. Knigge, Modeling of current spreading in high-power broad-area lasers and its impact on the lateral far field divergence, Preprint no. 2488, WIAS, Berlin, 2018, DOI 10.20347/WIAS.PREPRINT.2488 .
    Abstract, PDF (431 kByte)
    The effect of current spreading on the lateral far-field divergence of high-power broad-area lasers is investigated with a time-dependent model using different descriptions for the injection of carriers into the active region. Most simulation tools simply assume a spatially constant injection current density below the contact stripe and a vanishing current density beside. Within the drift-diffusion approach, however, the injected current density is obtained from the gradient of the quasi-Fermi potential of the holes, which solves a Laplace equation in the p-doped region if recombination is neglected. We compare an approximate solution of the Laplace equation with the exact solution and show that for the exact solution the highest far-field divergence is obtained. We conclude that an advanced modeling of the profiles of the injection current densities is necessary for a correct description of far-field blooming in broad-area lasers.

  • A. Pimenov, J. Javaloyes, S.V. Gurevich, A.G. Vladimirov, Light bullets in a time-delay model of a wide-aperture mode-locked semiconductor laser, Preprint no. 2481, WIAS, Berlin, 2018, DOI 10.20347/WIAS.PREPRINT.2481 .
    Abstract, PDF (5204 kByte)
    Recently, a mechanism of formation of light bullets (LBs) in wide-aperture passively modelocked lasers was proposed. The conditions for existence and stability of these bullets, found in the long cavity limit, were studied theoretically under the mean field (MF) approximation using a Haus-type model equation. In this paper we relax the MF approximation and study LB formation in a model of a wide-aperture three section laser with a long diffractive section and short absorber and gain sections. To this end we derive a nonlocal delay-differential equation (NDDE) model and demonstrate by means of numerical simulations that this model supports stable LBs. We observe that the predictions about the regions of existence and stability of the LBs made previously using MF laser models agree well with the results obtained using the NDDE model. Moreover, we demonstrate that the general conclusions based upon the Haus model that regard the robustness of the LBs remain true in the NDDE model valid beyond the MF approximation, when the gain, losses and diffraction per cavity round-trip are not small perturbations anymore.

  • A.G. Vladimirov, S.V. Gurevich, M. Tlidi, Effect of Cherenkov radiation on localized states interaction, Preprint no. 2480, WIAS, Berlin, 2018, DOI 10.20347/WIAS.PREPRINT.2480 .
    Abstract, PDF (2481 kByte)
    We study theoretically the interaction of temporal localized states in all fiber cavities and microresonator-based optical frequency comb generators. We show that Cherenkov radiation emitted in the presence of third order dispersion breaks the symmetry of the localized structrures interaction and greatly enlarges their interaction range thus facilitating the experimental observation of the dissipative soliton bound states. Analytical derivation of the reduced equations governing slow time evolution of the positions of two interacting localized states in a generalized Lugiato--Lefever model with the third order dispersion term is performed. Numerical solutions of the model equation are in close agreement with analytical predictions.

  • S. Amiranashvili, M. Radziunas, U. Bandelow, R. Čiegis, Numerical methods for accurate description of ultrashort pulses in optical fibers, Preprint no. 2470, WIAS, Berlin, 2018, DOI 10.20347/WIAS.PREPRINT.2470 .
    Abstract, PDF (2140 kByte)
    We consider a one-dimensional first-order nonlinear wave equation (the so-called forward Maxwell equation, FME) that applies to a few-cycle optical pulse propagating along a preferred direction in a nonlinear medium, e.g., ultrashort pulses in nonlinear fibers. The model is a good approximation to the standard second-order wave equation under assumption of weak nonlinearity. We compare FME to the commonly accepted generalized nonlinear Schrödinger equation, which quantifies the envelope of a quickly oscillating wave field based on the slowly varying envelope approximation. In our numerical example, we demonstrate that FME, in contrast to the envelope model, reveals new spectral lines when applied to few-cycle pulses. We analyze and compare pseudo-spectral numerical schemes employing symmetric splitting for both models. Finally, we adopt these schemes to a parallel computation and discuss scalability of the parallelization.

  • M. Radziunas, M. Khoder, V. Tronciu, J. Danckaert, G. Verschaffelt, Tunable semiconductor ring laser with filtered optical feedback: Traveling wave description and experimental validation, Preprint no. 2438, WIAS, Berlin, 2017, DOI 10.20347/WIAS.PREPRINT.2438 .
    Abstract, PDF (3116 kByte)
    We study experimentally and theoretically a semiconductor ring laser with four filtering channels providing filtered delayed optical feedback. To describe and analyze the wavelength selection and tuning in this device, we exploit the traveling-wave model determining the evolution of optical fields and carrier density along the ring cavity and filtering branches. The numerical results agree with the experimental observations: we can reproduce the wavelength tuning, the multiple wavelength emission, and the wavelength switching speed measured in these devices. The traveling-wave model allows us to study in detail the effect of the different laser parameters and can be useful for designing the future devices.

  • A. Grin, K.R. Schneider, Global bifurcation analysis of a class of planar systems, Preprint no. 2426, WIAS, Berlin, 2017, DOI 10.20347/WIAS.PREPRINT.2426 .
    Abstract, PDF (202 kByte)
    We consider planar autonomous systems dx/dt =P(x,y,λ), dy/dt =Q(x,y,λ) depending on a scalar parameter λ. We present conditions on the functions P and Q which imply that there is a parameter value λ0 such that for &lambda > λ0 this system has a unique limit cycle which is hyperbolic and stable. Dulac-Cherkas functions, rotated vector fields and singularly perturbed systems play an important role in the proof.

  • C. Brée, M. Hofmann, I. Babushkin, A. Demircan, U. Morgner, O.G. Kosareva, A.B. Savel'ev, A. Husakou, M. Ivanov, Symmetry breaking and strong persistent plasma currents via resonant destabilization of atoms, Preprint no. 2423, WIAS, Berlin, 2017, DOI 10.20347/WIAS.PREPRINT.2423 .
    Abstract, PDF (1839 kByte)
    The ionization rate of an atom in a strong optical field can be resonantly enhanced by the presence of long-living atomic levels (so called Freeman resonances). This process is most prominent in the multiphoton ionization regime meaning that ionization event takes many optical cycles. Nevertheless, here we show that these resonances can lead to fast subcycle-scale plasma buildup at the resonant values of the intensity in the pump pulse. The fast buildup can break the cycle-to-cycle symmetry of the ionization process, resulting in generation of persistent macroscopic plasma currents which remain after the end of the pulse. This, in turn, gibes rise to a broad-band radiation of unusual spectral structure forming a comb from terahertz (THz) to visible. This radiation contains fingerprints of the attosecond electronic dynamics in Rydberg states during ionization.

  • K. Schneider, New approach to study the van der Pol equation for large damping, Preprint no. 2422, WIAS, Berlin, 2017, DOI 10.20347/WIAS.PREPRINT.2422 .
    Abstract, PDF (237 kByte)
    We present a new approach to establish the existence of a unique limit cycle for the van der Pol equation in case of large damping which is hyperbolic and stable. The proof is based on a linear time scaling (instead of the nonlinear Liénard transformation), on a Dulac--Cherkas function and the property of rotating vector fields.

  • G. Slavcheva, M.V. Koleva, A. Pimenov, The impact of microcavity wire width on polariton soliton existence and multistability, Preprint no. 2381, WIAS, Berlin, 2017, DOI 10.20347/WIAS.PREPRINT.2381 .
    Abstract, PDF (5652 kByte)
    We have developed a model of the nonlinear polariton dynamics in realistic 3D non-planar microcavity wires in the driven-dissipative regime [15]. We find that the typical microcavity optical bistability evolves into multi-stability upon variation of the model parameters. The origin of the multi-stability is discussed in detail. We apply linear perturbation analysis to modulational instabilities, and identify conditions for localisation of composite multi-mode polariton solitons in the triggered parametric oscillator regime. Further, we demonstrate stable polariton soliton propagation in tilted and tapered waveguides, and determine maximum tilt angles for which solitons are still found. Additionally, we study soliton amplitude and velocity dependence on the wire width, with a view towards device applications.

Talks, Poster

  • M. Kantner, M. Mittnenzweig, Th. Koprucki, Semismooth Newton methods in PDE constrained optimization, SPIE Photonics West 2018: Physics and Simulation of Optoelectronic Devices XXVI, January 29 - February 1, 2018, The Moscone Center, San Francisco, USA, January 29, 2018.

  • M. Kantner, Thermodynamically consistent modeling of electrically driven quantum dot based light emitters on a device scale, Workshop ,,Nonlinear Dynamics in Semiconductor Lasers (NDSL2018)'', June 18 - 20, 2018, WIAS, Berlin, June 18, 2018.

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

  • A. Pimenov, Effect of chromatic dispersion in a delayed model of a mode-locked laser, Workshop ,,Nonlinear Dynamics in Semiconductor Lasers (NDSL2018)'', June 18 - 20, 2018, WIAS, Berlin, June 20, 2018.

  • U. Bandelow, Hierarchies of integrable NLS-type equations and selected solutions, 4th International Conference on Wave Interaction (WIN-2018), Johannes Kepler University Linz, Austria, April 4, 2018.

  • U. Bandelow, Ultrashort solitons and their control in the regime of event horizons in nonlinear dispersive optical media, George Stegeman Symposium, University of Central Florida, Orlando, USA, March 13, 2018.

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

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

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

  • M. Wolfrum, Phase solitons in DDEs with large delay, 14th IFAC Workshop on Time Delay Systems, June 28 - 30, 2018, Budapest University of Technology and Economics, Hungary, June 29, 2018.

  • S. Amiranashvili, Negative frequency radiation in optical fibers, Institutskolloquium, WIAS, Berlin, October 16, 2017.

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

  • C. Brée, Bloch mode transfer matrix method for photonic crystals, Internal seminar of the research group DONLL, Universitat Politecnica de Catalunya, Terrassa, Spain, July 12, 2017.

  • S. Eydam, Mode-locking in systems of globally coupled phase oscillators, Workshop on Control of Self-Organizing Nonlinear Systems, August 28 - 31, 2017, TU Berlin/SFB 910, Lutherstadt Wittenberg, August 31, 2017.

  • S. Eydam, Phase oscillator mode locking, SCL Seminar, Belgrade Institute of Physics, Serbia, September 28, 2017.

  • S. Eydam, Phase oscillator mode-locking, Forschungsseminar ``Applied Dynamical Systems'', TU Berlin, June 14, 2017.

  • M. Kantner, Hybrid quantum-classical modeling of electrically driven quantum light sources, Meeting of the MATHEON Scientific Advisory Board 2017, TU Berlin, Institut für Mathematik, November 13, 2017.

  • M. Kantner, Modeling of quantum dot based single-photon LEDs on a device level, MATHEON Workshop 10th Annual Meeting ``Photonic Devices'', February 9 - 10, 2017, Konrad-Zuse-Zentrum für Informationstechnik Berlin, February 10, 2017.

  • M. Kantner, Simulations of quantum dot devices by coupling of quantum master equations and semi-classical transport theory, 17th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD2017), July 24 - 28, 2017, Technical University of Denmark, Copenhagen, July 27, 2017.

  • A. Pimenov, Novel delayed model of a broad-area laser: Are the light bullets robust?, Minisymposium ,,Dynamics of novel mode-locked and frequency-swept lasers (DNMFL2017)'', December 18 - 19, 2017, WIAS, Berlin, December 18, 2017.

  • A. Pimenov, Temporal localized structures in a time delay model of a ring laser, International Workshop: Nonlinear Waves and Turbulence in Optics and Hydrodynamics, WIAS, Berlin, March 23, 2017.

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

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

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

  • U. Bandelow, Applied mathematical research in photonics at WIAS, Bosch-WIAS Workshop, WIAS, Berlin, June 13, 2017.

  • U. Bandelow, Few-cycle solitons that do not want to be too short in duration, CLEO Pacific Rim Conference, July 31 - August 4, 2017, The Optical Society, Singapore, Singapore, August 2, 2017.

  • U. Bandelow, Models for ultrashort optical pulses and their limiting soliton solutions, International Workshop: Nonlinear Waves and Turbulence in Optics and Hydrodynamics, WIAS, Berlin, March 22, 2017.

  • C. Brée, Detection of dynamic resonances in femtosecond filaments via the transient plasma grating effect, Workshop ,,Nonlinear Phenomena in Strong Fields'', Leibniz Universität Hannover, January 25, 2017.

  • C. Brée, Feedback-operator for a photonic crystal in the external cavity of a broad area laser diode, Forschungsseminar Mathematische Modelle der Photonik, WIAS, Berlin, June 22, 2017.

  • O. Omel'chenko, Bifurcations mediating appearance of chimera states, XXXVII Dynamics Days Europe, Minisymposium 3 ``Complex Networks: Delays And Collective Dynamics'', June 5 - 9, 2017, University of Szeged, Faculty of Science and Informatics, Hungary, June 8, 2017.

  • O. Omel'chenko, Bifurcations mediating the appearance of chimera states, SIAM Conference on Applications of Dynamical Systems (DS 17), Minisymposium ``Large Scale Dynamics In Coupled Systems On Networks'', May 21 - 25, 2017, Society for Industrial and Applied Mathematics (SIAM), Snowbird, USA, May 24, 2017.

  • O. Omel'chenko, Controlling unstable complex dynamics: From coupled oscillators to fluid mechanics, XV Latin American Workshop on NonLinear Phenomena, November 6 - 10, 2017, Facultad de Ciencias y Astronomía, Universidad de La Serena, Chile, November 7, 2017.

  • O. Omel'chenko, Introduction to chimera states, Seminar of the Scientific Computing Laboratory, University of Belgrade, Institue of Physics, Serbia, May 4, 2017.

  • O. Omel'chenko, Noninvasive model reconstruction from a partially synchronized state, XXXVII Dynamics Days Europe, Minisymposium 14b ``Synchronization Patterns In Networks: Theory and Applications'', June 5 - 9, 2017, University of Szeged, Faculty of Science and Informatics, Hungary, June 8, 2017.

  • O. Omel'chenko, Stabilizing control scheme: From chimera states to edge states, Internal seminar of the Prof. E. Knobloch group, Department of Physics, University of California, Berkeley, USA, May 17, 2017.

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

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

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

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

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

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

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

  • M. Wolfrum, Eine erstaunlich einfache Methode zur Berechnung des Sinus aus dem 16ten Jahrhundert, 22. Berliner Tag der Mathematik, Humboldt-Universität zu Berlin, April 22, 2017.

  • M. Wolfrum, Synchronization transitions in systems of coupled phase oscillators, IPB Colloquium, Institute of Physics Belgrade, Serbia, May 9, 2017.

  • M. Wolfrum, Chimera states in systems of coupled phase oscillators, Emerging Topics in Network Dynamical Systems, June 6 - 9, 2017, Lorentz Center, Leiden, Netherlands, June 6, 2017.

  • M. Wolfrum, Dynamics of coupled oscillator systems and their continuum limits, CIM-WIAS Workshop ``Topics in Applied Analysis and Optimisation'', December 6 - 8, 2017, International Center for Mathematics, University of Lisbon, Portugal, December 6, 2017.

External Preprints

  • A.G. Vladimirov, S.V. Gurevich, M. Tlidi, Effect of Cherenkov radiation on localized states interaction, Preprint no. arXiv:1707.04458, Cornell University Library, arXiv.org, 2017.
    Abstract
    We study theoretically the interaction of temporal localized states in all fiber cavities and microresonator-based optical frequency comb generators. We show that Cherenkov radiation emitted in the presence of third order dispersion breaks the symmetry of their interaction and greatly enlarges the interaction range thus facilitating the experimental observation of the soliton bound states. Analytical derivation of the reduced equations governing slow time evolution of the positions of two interacting localized states in the Lugiato-Lefever model with third order dispersion term is performed. Numerical solutions of the model equation are in close agreement with analytical predictions.