Temporal summation in a neuromimetic micropillar laser

Neuromimetic systems are systems mimicking the functionalities orarchitecture of biological neurons and may present an alternativepath for efficient computing and information processing. We demonstratehere experimentally temporal summation in a neuromimetic micropillarlaser with integrated saturable absorber. Temporal summation is theproperty of neurons to integrate delayed input stimuli and to respondby an all-or-none kind of response if the inputs arrive in a sufficientlysmall time window. Our system alone may act as a fast optical coincidence detector and paves the way to fast photonic spike processing networks

High density InAlAs/GaAlAs quantum dots for non-linear optics in microcavities

Structural and optical properties of InAlAs/GaAlAs quantum dots grown by molecular beam epitaxy are studied using transmission electron microscopy, temperature- and time resolvedphotoluminescence. The control of the recombination lifetime (50 ps – 1.25 ns), and of the dot density (5.10−8 – 2.1011 cm−3) strongly suggest that these material systems can find wide applications in opto-electronic devices as focusing non linear dispersive materials as well as fast saturable absorbers

Spike latency and response properties of an excitable micropillar laser

We present experimental measurements concerning the response of an excitable micropillar laser with saturable absorber to incoherent as well as coherent perturbations. The excitable response is similar to the behavior of spiking neurons but with much faster time scales. It is accompanied by a subnanosecond nonlinear delay that is measured for different bias pump values. This mechanism provides a natural scheme for encoding the strength of an ultrafast stimulus in the response delay of excitable spikes (temporal coding). Moreover, we demonstrate coherent and incoherent perturbations techniques applied to the micropillar with perturbation thresholds in the range of a few femtojoules. Responses to coherent perturbations assess the cascadability of the system. We discuss the physical origin of the responses to single and double perturbations with the help of numerical simulations of the Yamada model and, in particular, unveil possibilities to control the relative refractory period that we recently evidenced in this system. Experimental measurements are compared to both numerical simulations of the Yamada model and analytic expressions obtained in the framework of singular perturbation techniques. This system is thus a good candidate to perform photonic spike processing tasks in the framework of novel neuroinspired computing systems.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Interaction of two modulational instabilities in a semiconductor resonator

The interaction of two neighboring modulational instabilities in a coherently driven semiconductor cavity is investigated. First, an asymptotic reduction of the general equations is performed in the limit of a nearly vertical input-output characteristic. Next, a normal form is derived in the limit where the two instabilities are close to one other. An infinity of branches of periodic solutions are found to emerge from the unstable portion of the homogeneous branch. These branches have a nontrivial envelope in the bifurcation diagram that can either smoothly join the two instability points or form an isolated branch of solutions

Patterns and localized structures in bistable semiconductor resonators

We report experiments on spatial switching dynamics and steady state structures of passive nonlinear semiconductor resonators of large Fresnel number. Extended patterns and switching front dynamics are observed and investigated. Evidence of localization of structures is given.Comment: 5 pages with 9 figure

Nonlinear optics and saturation behavior of quantum dot samples under continuous wave driving

The nonlinear optical response of self-assembled quantum dots is relevant to the application of quantum dot based devices in nonlinear optics, all-optical switching, slow light and self-organization. Theoretical investigations are based on numerical simulations of a spatially and spectrally resolved rate equation model, which takes into account the strong coupling of the quantum dots to the carrier reservoir created by the wetting layer states. The complex dielectric susceptibility of the ground state is obtained. The saturation is shown to follow a behavior in between the one for a dominantly homogeneously and inhomogeneously broadened medium. Approaches to extract the nonlinear refractive index change by fringe shifts in a cavity or self-lensing are discussed. Experimental work on saturation characteristic of InGa/GaAs quantum dots close to the telecommunication O-band (1.24-1.28 mm) and of InAlAs/GaAlAs quantum dots at 780 nm is described and the first demonstration of the cw saturation of absorption in room temperature quantum dot samples is discussed in detail

Bistabilité optique des lasers couplés

On écrit le principe et les méthodes de réalisation d'une classe de bistable optique à basculement symétrique, basée sur l'inhibition réciproque de deux lasers à grand gain. L'analyse théorique permet de décrire les conditions d'obtention du régime bistable et les possibilités de commutation par voie purement optique. Une expérience menée avec une paire de lasers à colorant confirme la validité de ce principe et démontre la possibilité de commutations sub-nanoseconde. L'extension aux lasers à semi-conducteurs est discutée et les caractéristiques fonctionnelles de ces dispositifs sont comparées à celles des autres bistables optiques