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1998, Physica D: Nonlinear Phenomena
The model equations of a semiconductor laser with delayed feeback are studied as a prototype of general delayed systems in the case of long delay (thermodynamic limit). It is shown that its behaviour in the vicinity of the Hopf bifurcation can be described by suitable amplitude equations. The derivation of the final model follows naturally from the space-time representation of the evolution and by the corresponding re-formulation of the linear stability problem. Regions characterized by both direct and inverse Hopf bifurcations are found, and in particular, parameter values are identified for which a chaotic evolution is expected.
Siam Journal on Applied Mathematics, 2000
Hopf bifurcation theory for an oscillator subject to a weak feedback but a large delay is investigated for a specific laser system. The problem is motivated by semiconductor laser instabilities which are initiated by undesirable optical feedbacks. Most of these instabili- ties start from a single Hopf bifurcation. Because of the large delay, a delayed amplitude appears in the slow
Physica D: Nonlinear Phenomena, 1992
Asymptotic solutions of nonlinear differential-difference equations describing the lasing dynamics with a negative feedback are obtained. Periodic lasing regimes with a complex relaxational structure are shown to be possible in such lasers. The phenomenon of multistability, i.e., the co-existence of a great number of structurally different and structurally similar attractors, is analytically described. Asymptotic characteristics of lasing regimes (pulse shape and radiation pulsation frequency) are found and the domains in the parameter space and the initial conditions for their realization are determined for all types of solution. The chaotic dynamics following the sequence of period-doubling bifurcations is also numerically determined.
2011
Delayed feedback laser dynamics is described by means of Lang-Kobayashi equation model. Since a lot of initial states asymptotically approach to periodic attractor in the phase space, only periodic steady-state regimes have been studied here. Lyapunov transformation allows us to reduce problem to the differential equation of the first order whereas the spectrum of laser oscillation is governed by the
Physical Review E, 2014
We present a detailed experimental characterization of the autocorrelation properties of a delayed feedback semiconductor laser for different dynamical regimes. We show that in many cases the autocorrelation function of laser intensity dynamics can be approximated by the analytically derived autocorrelation function obtained from a linear stochastic model with delay. We extract a set of dynamic parameters from the fit with the analytic solutions and discuss the limits of validity of our approximation. The linear model captures multiple fundamental properties of delay systems, such as the shift and asymmetric broadening of the different delay echoes. Thus, our analysis provides significant additional insight into the relevant physical and dynamical properties of delayed feedback lasers.
Quantum Electronics, 2008
The appearance of oscillating regimes in a delayed feedback diode laser is studied analytically and numerically. Based on the Lang ë Kobayashi model, the transition of the usual oscillation mechanism, related to the transition through the Hopf bifurcation, to hard excitation of the spike regime is studied. The change in the regime of the instability development has a nature of a phase transition. An explicit expression is derived for the frequency of small harmonic oscillations appearing during the transition through the Andronov ë Hopf bifurcation. The boundary between two different regimes of the development of laser power oscillations is determined in the parameter space.
Physical Review Letters, 2001
We give experimental and numerical evidence for a new dynamical regime in the operation of semiconductor lasers subject to delayed optical feedback occurring for short delay times. This short cavity regime is dominated by a striking dynamical phenomenon: regular pulse packages forming a robust low-frequency state with underlying fast, regular intensity pulsations. We demonstrate that these regular pulse packages correspond to trajectories moving on global orbits comprising several destabilized fixed points within the complicated phase space structure of this delay system.
Handbook of Chaos Control, 2007
The light emitted by a broad-area semiconductor laser is spectacularly bright but at the same time generally displays vivid spatiotemporal and even chaotic dynamics. This very "un-laser-like" feature is a footprint of the complex interplay of ultrafast carrier and light-field dynamics within the laser leading to spatiospectral hole burning, light diffraction and self-focusing. From the viewpoint of application, the stabilization and control of the chaotic dynamics of semiconductor lasers clearly is most important. However, this task is here particularly challenging since the large cavity width needed for achieving the high output signal leads to a complex spatiospectral mode dynamics. One thus has to find ways to control a continuum of spatial, temporal, and even spectrally dependent processes. This chapter presents modeling results of the complex spatiotemporal and spatiospectral dynamics of large-area lasers controlled by delayed optical feedback. Our theory is based on a Maxwell-Bloch approach taking into account the transverse and longitudinal dependence of the light fields and the charge carriers. Results of the spatially and temporally resolved simulations open a way to an identification of parameter regimes-such as length of the delay line and feedback strength-where an optimum control can be achieved and show the importance of a fundamental analysis for the understanding of the physical processes within the laser structure. This may pave the way for the development and design of novel control schemes for semiconductor lasers with optimized spatial and spectral emission characteristics.
We report a numerical characterization of the stability of semiconductor lasers with delayed feedback under the simultaneous variation of the delay time τ and the pump current P . Changes in the number of External Cavity Modes are studied as a function of the delay time while the Regular Pulse Package regime is characterized as a function of the pump current. In addition, we describe some remarkable structures observed in the τ × P control plane, delimiting where these and other complex regimes of laser operation exist.
Physical Review Letters, 1994
Chaos, Solitons & Fractals, 2005
The trivial equilibrium of a nonlinear autonomous system with time delay may become unstable via a Hopf bifurcation of multiplicity two, as the time delay reaches a critical value. This loss of stability of the equilibrium is associated with two coincident pairs of complex conjugate eigenvalues crossing the imaginary axis. The resultant dynamic behaviour of the corresponding nonlinear non-autonomous system in the neighbourhood of the Hopf bifurcation is investigated based on the reduction of the infinite-dimensional problem to a four-dimensional centre manifold. As a result of the interaction between the Hopf bifurcating periodic solutions and the external periodic excitation, a primary resonance can occur in the forced response of the system when the forcing frequency is close to the Hopf bifurcating periodic frequency. The method of multiple scales is used to obtain four first-order ordinary differential equations that determine the amplitudes and phases of the phase-locked periodic solutions. The first-order approximations of the periodic solutions are found to be in excellent agreement with those obtained by direct numerical integration of the delaydifferential equation. It is also found that the steady state solutions of the nonlinear non-autonomous system may lose their stability via either a pitchfork or Hopf bifurcation. It is shown that the primary resonance response may exhibit symmetric and asymmetric phase-locked periodic motions, quasi-periodic motions, chaotic motions, and coexistence of two stable motions.
Physical Review E, 2003
We present a comprehensive study of the emission dynamics of semiconductor lasers induced by delayed optical feedback from a short external cavity. Our analysis includes experiments, numerical modelling and bifurcation analysis by means of computing unstable manifolds. This provides a unique overview and a detailed insight into the dynamics of this technologically important system and into the mechanisms leading to delayed feedback instabilities. By varying the external cavity phase we find a cyclic scenario leading from stable intensity emission via periodic behavior to regular and irregular pulse packages, and finally back to stable emission. We reveal the underlying interplay of localized dynamics and global bifurcations.
Optics Communications, 2004
We study the behaviour of a semiconductor laser subject to phase-conjugate feedback when the interaction time of the phase-conjugating mirror changes. With continuation techniques we present two-parameter bifurcation diagrams in the plane of feedback strength versus pump current, which change qualitatively as the interaction time of the mirror is increased. This reveals that for small interaction times the assumption of instantaneous feedback is justified. On the other hand, increasingly larger interaction times lead to considerable changes in the locking region. By investigating how curves of Hopf bifurcations change with the interaction time, we show how more complicated, chaotic dynamics become suppressed. One-parameter bifurcation diagrams as a function of the pump current, obtained by simulation, complement the continuation analysis.
Physics Letters A, 1996
We report on the first analysis of the influence of delayed optical feedback on the spatio-temporal dynamics of spatially extended semiconductor laser devices. We start our investigation with the single-stripe laser, where we discuss analogies and differences to common plane-wave models. In the case of the twin-stripe laser, we find that, depending on parameter values, delayed optical feedback may on the one hand cause spatio-temporal instabilities leading to spatio-temporal chaos, and on the other hand induce coherent regimes in an originally chaotic state.
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2019
Time delays play an important role in many fields such as engineering, physics or biology. Delays occur due to finite velocities of signal propagation or processing delays leading to memory effects and, in general, infinite-dimensional systems. Time delay systems can be described by delay differential equations and often include non-negligible nonlinear effects. This overview article introduces the theme issue ‘Nonlinear dynamics of delay systems’, which contains new fundamental results in this interdisciplinary field as well as recent developments in applications. Fundamentally, new results were obtained especially for systems with time-varying delay and state-dependent delay and for delay system with noise, which do often appear in real systems in engineering and nature. The applications range from climate modelling over network dynamics and laser systems with feedback to human balancing and machine tool chatter. This article is part of the theme issue ‘Nonlinear dynamics of delay...
Optics Communications, 2012
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IEEE Journal of Quantum Electronics, 2009
A critical issue in optical chaos-based communications is the possibility to identify the parameters of the chaotic emitter and, hence, to break the security. In this paper, we study theoretically the identification of a chaotic emitter that consists of a semiconductor laser with an optical feedback. The identification of a critical security parameter, the external-cavity round-trip time (the time delay in the laser dynamics), is performed using both the auto-correlation function and delayed mutual information methods applied to the chaotic time-series. The influence on the time-delay identification of the experimentally tunable parameters, i.e., the feedback rate, the pumping current, and the time-delay value, is carefully studied. We show that difficult time-delay-identification scenarios strongly depend on the time-scales of the system dynamics as it undergoes a route to chaos, in particular on how close the relaxation oscillation period is from the external-cavity round-trip time.
EPL (Europhysics …, 1998
PACS. 02.30Ks -Delay and functional equations. PACS. 05.45+b -Theory and models of chaotic systems.
SPIE Proceedings, 2002
A semiconductor laser subject to phase-conjugate optical feedback can be described by rate equations, which are mathematically delay differential equations (DDEs) with an infinite dimensional phase space. This is why, from the theoretical point of view, this system was only studied by numerical simulation up to now. We employ new numerical techniques for DDEs, namely the continuation of periodic orbits and the computation of unstable manifolds, to study bifurcations and routes to chaos in the system. Specifically we compute 1D unstable manifolds of a saddle-type periodic orbit as intersection curves in a suitable Poincaré section. We are able to explain in detail a transition to chaos as the feedback strength is increased, namely the break-up of a torus and a sudden transition to chaos via a boundary crisis. This allows us to make statements on properties of the ensuing chaotic attractor, such as its dimensionality. Information of this sort is important for applications of chaotic laser signals, for example, in communication schemes.
International Journal of Bifurcation and Chaos, 1998
We investigate the influence of delayed optical feedback (DOF) on the dynamics of semiconductor lasers. In the case of the narrow single-stripe laser, we find that the presence of DOF leads to a wealth of dynamical phenomena in the coherence-collapsed regime, including mode-hopping between compound-cavity modes induced by DOF. Focusing on the twin-stripe laser — the most simple system with inherent spatio-temporal instabilities — we show that feedback may both induce and suppress spatio-temporal instabilities. Eigenmode analysis enables us to determine and identify the underlying spatio-temporal "supermodes". For appropriately chosen parameters, regular regimes including continuous wave operation can be obtained from an originally chaotic regime. For moderate to strong feedback, interaction between the spatial degrees of freedom in the twin-stripe laser and the compound cavity modes leads to a new phenomenon which we term "spatio-temporal mode-hopping".
2004
This paper considers a system of two semiconductor lasers that are mutually coupled face to face, so that they receive each other's light after a delay time τ. The lasers are assumed to be identical, except for a possible detuning ∆ of their free-running frequencies. The coupled laser modes of a rate equation model with delay are studied with tools from bifurcation theory, especially numerical continuation. This reveals a comprehensive geometrical picture, which is organized by the unfoldings for ∆ = 0 of pitchfork bifurcations that exists for ∆ = 0.
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