Spatiotemporal communication with synchronized optical chaos

We propose a model system that allows communication of spatiotemporal information using an optical chaotic carrier waveform. The system is based on broad-area nonlinear optical ring cavities, which exhibit spatiotemporal chaos in a wide parameter range. Message recovery is possible through chaotic synchronization between transmitter and receiver. Numerical simulations demonstrate the feasibility of the proposed scheme, and the benefit of the parallelism of information transfer with optical wavefronts.Comment: 4 pages, 5 figure

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

Performance characteristics of positive and negative delayed feedback on chaotic dynamics of directly modulated InGaAsP semiconductor lasers

The chaotic dynamics of directly modulated semiconductor lasers with delayed optoelectronic feedback is studied numerically. The effects of positive and negative delayed optoelectronic feedback in producing chaotic outputs from such lasers with nonlinear gain reduction in its optimum value range is investigated using bifurcation diagrams. The results are confirmed by calculating the Lyapunov exponents. A negative delayed optoelectronic feedback configuration is found to be more effective in inducing chaotic dynamics to such systems with nonlinear gain reduction factor in the practical value range.Comment: 18 pages, 16 figures. To appear In Pramana - journal of physic

Réduction par échange protonique de la tension d'accord de phase dans un convertisseur TE-TM

A method for reducing phase matching voltages by a factor 4 in TE-TM convertors is described. The method is illustrated with the fabrication of a $Y$-cut $Z$-propagating, TI-PE LiNbO$_3$, mode convertor. Mode conversion is achieved using an electric field $E_X$, while an electric field $E_y$ performs phase-matching. Depression of the surface index of the Ti : LiNbO$_3$ waveguide by proton exchange forms a H$_x$Li$_{l - x}$NbO$_3$ buffer layer that reduces phase-mismatching and permits to obtain a phase-matching voltage down to 7 volts at 1.15 $\mu$m.On propose dans cet article de réduire d'un facteur 4 l'écart entre les indices effectifs des modes TE et TM se propageant parallèlement à l'axe $Z$ dans un convertisseur actif de polarisation réalisé à partir d'un guide d'onde en titane diffusé dans LiNbO$_3$ de coupe $Y$. La conversion modale est assurée par un champ électrique $E_X$, tandis que l'accord de phase compensant la biréfringence modale entre les modes est obtenue avec un champ $E_y$. La méthode proposée consiste à créer par échange protonique une mince couche de H$_x$Li$_{l - x}$NbO$_3$ d'indice légèrement inférieur à celui du substrat de manière à diminuer le désaccord de phase. La tension d'accord de phase obtenue est réduite à 7 volts à 1,15 $\mu$m

Correlateur opto-electronique analogique pour le traitement en parallele de signaux de type radar

On propose une nouvelle architecture de corrélalateur acousto-optique par intégration dans le temps qui permet de tirer parti des largeurs spectrales d'émission des sources, jusqu'à présent inexploitées en traitement du signal. L'intérêt réside dans la possibilité de traiter plusieurs signaux en temps réel. Les expériences de faisabilité ont été menées sur des signaux simples, avec des composants massifs (modulateurs électro et acousto-optiques) et une diode laser multimode. A l'issue de cette étude, les perspectives portent sur la réalisation d'autres types de processeurs développés en traitement radar tels qu'analyseurs de spectres multicanaux à haute résolution. Une seconde perspective concerne l'intégration des composants sur LiNb03 pour améliorer les performances

Improved LiNbO3 technology for reducing sidelobe asymmetry in mode converter-based wavelength filters

International audienceWe present an experimental explanation of the sidelobe amplitude increase generally observed in LiNbO3 polarization converter-based wavelength filters. We propose a simple improved LiNbO3 process to avoid this problem and show experimental results that confirm our hypothesis

Limitations imposed by LiNbO3-integrated optics technology on narrow-linewidth filters based on mode coupling

International audienceIntegrated tunable narrow-linewidth wavelength filters based on TE-TM mode conversion require a high quality processing. The discussion is based on numerical simulations of typical technology-induced defects and on a comparison with experimental results. We show that uniformity of the LiNbO3 crystal growth currently limits the linewidth to about 0.6 nm for spectral filters operating at 1.55 mm. Moreover, such a filter would require a technology with strict conditions of uniformity over several centimeters. The discussion is focused on electro-optic filters but the results can be extended to any device based on codirectional mode coupling, such as acousto-optic filters

Subcritical Hopf bifurcation in dynamical systems described by a scalar nonlinear delay differential equation

A subcritical Hopf bifurcation in a dynamical system modeled by a scalar nonlinear delay differential equation is studied theoretically and experimentally. The subcritical Hopf bifurcation leads to a significant domain of bistability where stable steady and time-periodic states coexist.Journal Articleinfo:eu-repo/semantics/publishe