Time delays in the synchronization of chaotic coupled lasers with feedback (original) (raw)
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Synchronization of chaotic semiconductor laser systems: a vectorial coupling-dependent scenario
Physical review letters, 2002
We demonstrate the influence of vectorial coupling on the synchronization behavior of complex systems. We study two semiconductor lasers subject to delayed optical feedback which are unidirectionally coherently coupled via their optical fields. Our experimental and numerical results demonstrate a characteristic synchronization scenario in dependence on the relative feedback phase leading cyclically from chaos synchronization to almost uncorrelated states, and back to chaos synchronization. Finally, we reveal the influence of the feedback phase on the dynamics of the solitary delay system.
Synchronization by injection of common chaotic signal in semiconductor lasers with optical feedback
Optics Express, 2009
We investigate the dynamics of two semiconductor lasers with separate optical feedback when they are driven by a common signal injected from a chaotic laser under the condition of non-identical drive and response. We experimentally and numerically show conditions under which the outputs of the two lasers can be highly correlated with each other even though the correlation with the drive signal is low. In particular, the effects of the phase of the feedback light on the correlation characteristics are described. The maximum correlation between the two response lasers is obtained when the phase of the feedback light is matched between the two response lasers, while the minimum correlation is observed when the difference in the optical phase is π. On the other hand, the correlation between the drive and response is not sensitive to the phase of the feedback light, unlike the previously studied case of identical drive and response. We numerically examine the difference between the maximum and minimum cross correlations over a wide range of parameters, and show that it is largest when there is a balance between the injection strength and the feedback strength.
Physical Review E, 2002
We numerically study the synchronization of two unidirectionally coupled single-mode semiconductor lasers in a master-slave configuration. The master laser is an external-cavity laser that operates in a chaotic regime while for the slave laser we consider two configurations. In the first one, the slave laser is also an externalcavity laser, subjected to, its own optical feedback and the optical injection from the master laser. In the second one, the slave laser is subject only to the optical injection from the master laser. Depending on the operating conditions the synchronization between the two lasers, whenever it exists, can be either isochronous or anticipated. We perform a detailed study of the parameter regions in which these synchronization regimes occur and how small variations of parameter yield one or the other type of synchronization or an unsynchronized regime.
Physical Review A, 2000
We present experimental evidence for the synchronization of two semiconductor lasers exhibiting chaotic emission on subnanosecond time scales. The transmitter system consists of a semiconductor laser with weak to moderate coherent optical feedback and therefore exhibits chaotic oscillations. The receiver system is realized by a solitary semiconductor laser in which a fraction of the transmitter signal is coherently injected. We find that for a considerably large parameter range, synchronized receiver output can be achieved. We discuss the physical mechanism and demonstrate that the receiver acts as a chaos pass filter, which reproduces the chaotic fluctuations of the transmitter laser, but suppresses additionally encoded signals. Signal extraction at frequencies of up to 1 GHz has been achieved. Thus we provide a simple and robust optical chaos synchronization system that is promising for the realization of communication by sending signals with chaotic carriers.
Optical spectrum behaviour of a coupled laser system under chaotic synchronization conditions
Journal of the European Optical Society: Rapid Publications, 2013
Synchronization characteristics of two bidirectionally coupled semiconductor lasers, one operating in a chaotic regime with low-frequency fluctuations and the other with free laser beam emission, were experimentally investigated. The chaotic synchronization regimes and optical spectral behavior of the coupled system were analyzed with respect to the optical spectra emitted initially by the two uncoupled lasers operated under the same feedback conditions. It was observed that the number of synchronization regimes that can be obtained and their stability depend on the similarity of spectral structures of the uncoupled lasers emissions. The dominant active laser modes of the coupled system emission coincide with the laser modes of the one or both uncoupled laser emissions, depending on the operating synchronization regime. We have associated changes in the optical spectrum of the coupled system with the synchronization regimes. The repartition of power between the active modes of a coupled system allows identification of the synchronization regime.
Chaos-Synchronization In Semiconductor Laser Systems: An Optical Phase-Dependent Scenario
Experimental Chaos, 2002
Synchronization of chaotic oscillators is of high current interest in various areas of science. Semiconductor laser systems offer a great potential for experimental studies of synchronization phenomena, because of well-controllable parameters, wellstudied nonlinear dynamical behavior and their broad spectrum of applications. We investigate chaos-synchronization of two unidirectionally coupled semiconductor lasers with delayed optical feedback. We present a characteristic synchronization scenario in dependence of the relative optical cavity phase of the subsystems. For adjusted phase, we find excellent synchronization of the intensity dynamics in combination with coherence among the emitted fields of the lasers, despite of the fast chaotic wavelengthfluctuations. Variation of the phase leads to conspicuous changes in the intensitydynamics associated with drastically reduced correlation and loss of coherence among the lasers. Our results provide insight into the consequences of vectorial coupling for the synchronization scenario and open the perspective for innovative concepts for encrypted GHz data communication.
Chaos synchronization in networks of delay-coupled lasers: role of the coupling phases
New Journal of Physics, 2012
We derive rigorous conditions for the synchronization of alloptically coupled lasers. In particular, we elucidate the role of the optical coupling phases for synchronizability by systematically discussing all possible network motifs containing two lasers with delayed coupling and feedback. By these means we explain previous experimental findings. Further, we study larger networks and elaborate optimal conditions for chaos synchronization. We show that the relative phases between lasers can be used to optimize the effective coupling matrix.
Synchronization of Mutually Coupled Chaotic Lasers in the Presence of a Shutter
Physical Review Letters, 2007
Two mutually coupled chaotic diode lasers exhibit stable isochronal synchronization in the presence of self feedback. When the mutual communication between the lasers is discontinued by a shutter and the two uncoupled lasers are subject to self-feedback only, the desynchronization time is found to scale as A d τ where A d > 1 and τ corresponds to the optical distance between the lasers. Prior to synchronization, when the two lasers are uncorrelated and the shutter between them is opened, the synchronization time is found to be much shorter, though still proportional to τ . As a consequence of these results, the synchronization is not significantly altered if the shutter is opend/closed faster than the desynchronization time. Experiments in which the coupling between two chaotic-synchronized diode lasers is modulated with an electro-optic shutter are found to be consistent with the results of numerical simulations.
Numerical analysis of chaos synchronization in semiconductor lasers subject to a common drive signal
Electronics and Communications in Japan, 2010
Chaos synchronization of two semiconductor lasers commonly driven by a chaotic semiconductor laser subject to optical feedback was observed. Strongly correlated chaos synchronization between the two response lasers was observed even when the correlation between the drive and response lasers was low. It is shown that the cross correlation between the two responses is larger than that between the drive and response lasers over a wide parameter region.
Chapter 1. Control and Synchronization in Chaotic Lasers: Experiments, Models and Application
Recent Achievements in Laser Dynamics: Control and Synchronization, 2008
We present methods able to control chaotic dynamics as well as to suppress bursting phenomena emerging in a modulated laser as a consequence of an internal crisis. We also discuss the problem of attractor selection in a bistable regime with jumps between independent attractors. Furthermore, we report on different forms of synchronization of coupled lasers. Identical phase and generalized synchronization will be discussed in autonomous and non autonomous systems dealing with class-B lasers.