Third 'Rio De La Plata' Workshop on Noise, Chaos, and Complexity in Lasers and Nonlinear Optics (original) (raw)
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Broadband Chaos Generated by an Optoelectronic Oscillator
Physical Review Letters, 2010
We study an opto-electronic time-delay oscillator that displays high-speed chaotic behavior with a flat, broad power spectrum. The chaotic state coexists with a linearly-stable fixed point, which, when subjected to a finite-amplitude perturbation, loses stability initially via a periodic train of ultrafast pulses. We derive approximate mappings that do an excellent job of capturing the observed instability. The oscillator provides a simple device for fundamental studies of time-delay dynamical systems and can be used as a building block for ultra-wide-band sensor networks.
Coherence Resonance in Optical Feedback Chaos: Hiding Frequency in Chaos Communication
Chaos Theory
In this chapter, an experimentally and numerically conducted investigation of the existence of high chaotic spiking in the dynamics of semiconductor lasers with AC-coupled optical feedback, the bifurcation diagram by feedback strength attenuation and the bias current as a control parameter was done. A semiconductor laser subjected to an external optical feedback can present a big change of dynamic behaviors, such as periodic and quasiperiodic oscillations, chaos, coherence collapse, and low-frequency fluctuations (LFF's) that degrade the laser characteristics. The chaotic instability is experimentally investigated on feedback strength as a control parameter, and the resulted dynamic is monostability. Finally, we indicated that the observed chaotic dynamic is a good candidate to hide information in order to investigate the resonance phenomena, which is important for chaos to encrypt data in optical communication, where data disappear when modulated in a chaos carrier. The aim of this chapter is to investigate the encryption area in the chaotic system when the applied frequency is 1-500 MHz, for satisfying the secure communication.
Chaos and high-level dynamics in coupled lasers and their applications
Progress in Quantum Electronics, 2012
In this paper, we first introduce mutual and self-coupling and related phenomena in laser diodes, and discuss how the chaos paradigm has been unveiled as a refinement of classical Adler's locking equation describing coupling. Then, we take the ICL (injected coupled laser) system as a reference and illustrate the newly found regimes of injection modulations, labile locking, periodicity and multiperiodicity, chaos, opening and closing bifurcations, up to the final locking of the system. Analysis is carried out by Lamb and Kobayashi equations, in good agreement with experiments. The concept of synchronization is then developed and schemes devised to implement it on an ICL system are discussed. We then show that two cryptography schemes easily follow from synchronization, namely CM (chaos masking) and CSK (chaos shift keying), and describe some implementations of them as well as the results of a sensitivity analysis. After that, we broaden the range of applicabil`ıty of coupled phenomena showing they are robust against change of parameters and configurations. As a preferred, minimum part-count scheme useful for engineering implementation, we then introduce and evaluate the DOF (delayed optical feedback) configuration, basically a self-mixing scheme operating at a high level of (self)-coupling. For the DOF system, we run through the paradigm of high level dynamics, synchronization and cryptography variants (CM and CSK) again, and find that this system is well suited to all application criteria. We describe practical and in-field implementation of cryptography schemes, CM as well as the PIC (photonics integrated circuit) devices reported so far. A system analysis is then presented, with a summary of experiments on variants of basic cryptography scheme, and some general considerations about cryptography codes and robustness. Finally, we briefly digress to illustrate the recent field of noncryptography applications of optical chaos systems, such as random number generation, distance measurement, and microwave photonics.
Feedback Phase in Optically Generated Chaos: A Secret Key for Cryptographic Applications
IEEE Journal of Quantum Electronics, 2000
The feedback phase in a chaotic system consisting of a semiconductor laser subject to delayed optical feedback is considered for the first time as a secret key for secure chaotic communications not exclusively based on hardware uniqueness. Extensive numerical simulations illustrate that the feedback phase is of extreme importance as far as synchronization is concerned. The ability of an eavesdropper to attack the intensity-modulated message when a pseudorandom variation of the feedback phase is imposed at the transmitter's side is numerically quantified by bit-error-rate calculations. The analysis demonstrates that the eavesdropper is not able to synchronize and hence to extract the message when he is not aware of the phase variations even if he is equipped with an identical chaotic device.
Optics …, 2011
In the dynamics of optical systems, one commonly needs to cope with the problem of coexisting deterministic and stochastic components. The separation of these components is an important, although difficult, task. Often the time scales at which determinism and noise dominate the system's dynamics differ. In this Letter we propose to use information-theory-derived quantifiers, more precisely, permutation entropy and statistical complexity, to distinguish between the two behaviors. Based on experiments of a paradigmatic opto-electronic oscillator, we demonstrate that the time scales at which deterministic or noisy behavior dominate can be identified. Supporting numerical simulations prove the accuracy of this identification.
Synchronization properties of chaotic semiconductor lasers and applications to encryption
Comptes Rendus Physique, 2004
We review the main properties of two unidirectionally coupled single-mode semiconductor lasers (master-slave configuration). Our analysis is based on numerical simulations of a rate equations model. The emitter, or master laser, is assumed to be an external-cavity single-mode semiconductor laser subject to optical feedback that operates in a chaotic regime. The receiver, or slave laser, is similar to the emitter but can either operate in a chaotic regime, as the emitter closed loop configuration), or without optical feedback and consequently under CW when it is uncoupled (open loop configuration). This configuration is one of the most simple and useful configuration for chaos based communication systems and data encryption. To cite this article: C.R. Mirasso et al., C. R. Physique 5 (2004). 2004 Académie des sciences. Published by Elsevier SAS. All rights reserved.
Physical Review E, 2009
We demonstrate experimentally how nonlinear optical phase dynamics can be generated with an electrooptic delay oscillator. The presented architecture consists of a linear phase modulator, followed by a delay line, and a differential phase-shift keying demodulator ͑DPSK-d͒. The latter represents the nonlinear element of the oscillator effecting a nonlinear transformation. This nonlinearity is considered as nonlocal in time since it is ruled by an intrinsic differential delay, which is significantly greater than the typical phase variations. To study the effect of this specific nonlinearity, we characterize the dynamics in terms of the dependence of the relevant feedback gain parameter. Our results reveal the occurrence of regular GHz oscillations ͑approximately half of the DPSK-d free spectral range͒, as well as a pronounced broadband phase-chaotic dynamics. Beyond this, the observed dynamical phenomena offer potential for applications in the field of microwave photonics and, in particular, for the realization of novel chaos communication systems. High quality and broadband phase-chaos synchronization is also reported with an emitter-receiver pair of the setup.