Physics and Applications of Laser Diode Chaos

An overview of chaos in laser diodes is provided which surveys experimental achievements in the area and explains the theory behind the phenomenon. The fundamental physics underpinning this behaviour and also the opportunities for harnessing laser diode chaos for potential applications are discussed. The availability and ease of operation of laser diodes, in a wide range of configurations, make them a convenient test-bed for exploring basic aspects of nonlinear and chaotic dynamics. It also makes them attractive for practical tasks, such as chaos-based secure communications and random number generation. Avenues for future research and development of chaotic laser diodes are also identified.Comment: Published in Nature Photonic

Encryption using chaotic dynamics for optical telecommunications

Chaos-based encryption appeared recently in the early 1990s as an original application of nonlinear dynamics in the chaotic regime. While the first experimental realizations were made in Electronics, the Optics community rapidly showed a strong interest in this new scientific application due to the well-known feature of Optics in the area of nonlinear phenomena. Numerous optical demonstrations have been performed, involving chaotic dynamics with particularly interesting properties in terms of chaos complexity, and also in terms of bandwidth i.e., encryption speed. This special issue gives a review of most of the current works on optical chaos dedicated to encryption

Transmission system using chaotic delays between lightwaves

We report a chaos-based transmission system that uses optical path differences between wavegroups produced by a short coherence source. Chaos synchronization is demonstrated in delay-differential equations involving optical delays larger than the coherence length of the source. The particular feature is all-optical chaos subtraction for message extraction and a very high masking efficiency

LiNbO3 Mach-Zehnder modulator with chirp adjusted by ferroelectric domain inversion

Domain inversion under coplanar waveguide electrodes is proposed to improve the frequency-chirping behavior of z-cut LiNbO/sub 3/ Mach-Zehnder modulators. This is achieved by introducing phase reversal electrode section in tandem with inverted ferroelectric domain section. The resulting chirp is shown to be related to the length of the inverted domain. The method opens the way to single-drive modulators with predetermined chirp parameter. The fabrication of such modulators is described, and experimental results confirm that the /spl alpha/-chirp parameter can be more than ten times smaller than that of a conventional Z-cut device

Demonstration of a chaos generator with two time delays

We demonstrate a chaos generator involving two time delays and two nonlinear functions. Dynamic behaviors are numerically and experimentally observed. The complexity of the dynamics is discussed in terms of Lyapunov exponents and dimensions. The setup can provide a new architecture for enhancing message security in chaos encryption systems

Cracking chaos-based encryption systems ruled by nonlinear time delay differential equations

We report that signal encoding with high-dimensional chaos produced by delayed feedback systems with a strong nonlinearity can be broken. We describe the procedure and illustrate the method with chaotic waveforms obtained from a strongly nonlinear optical system that we used previously to demonstrate signal encryption/decryption with chaos in wavelength. The method can be extended to any systems ruled by nonlinear time-delayed differential equations

Communicating with hyperchaos: The dynamics of a DNLF emitter and recovery of transmitted information

It is reported that signal encoding with high-dimensional chaos produced by delayed feedback systems with strong nonlinearity can be broken. The procedure is described and the method is illustrated with chaotic waveforms obtained from a strongly nonlinear optical system used by the authors previously to demonstrate signal encryption and decryption with wavelength chaos. The method can be extended to any systems ruled by nonlinear time-delayed differential equations