Cavity Soliton Laser based on mutually coupled semiconductor microresonators

We report on experimental observation of localized structures in two mutually coupled broad-areahttp://hal.archives-ouvertes.fr/images/calendar.gif semiconductor resonators. These structures coexist with a dark homogeneous background and they have the same properties as cavity solitons without requiring the presence of a driving beam into the system. They can be switched individually on and off by means of a local addressing beam

All-optical delay line using semiconductor cavity solitons

An all-optical delay line based on the lateral drift of cavity solitons in semiconductor microresonators is proposed and experimentally demonstrated. The functionalities of the device proposed as well as its performance is analyzed and compared with recent alternative methods based on the decrease of group velocity in the vicinity of resonances. We show that the current limitations can be overcome using broader devices with tailored material responses

All-optical delay line using semiconductor cavity solitons (vol 92, 011101, 2008)

Correction of Pedaci, F. and Barland, S. and Caboche, E. and Firth, W.J. and Oppo, G.L. and Tredicce, J.R. and Ackemann, T. and Scroggie, A.J. (2008) All-optical delay line using semiconductor cavity solitons. Applied Physics Letters, 92 (1). ISSN 0003-695

Susceptibility synthesis of arbitrary shaped metasurfaces

International audienceVisual perception relies on light scattering at the object's surface in the direction of observation. By engineering the surface scattering properties, it is possible to realize arbitrary visual percept. Here, we address theoretically this problem of electromagnetic field transition conditions at conformal interfaces to achieve surface topography-dependent transmitted and reflected fields. Our analysis, supported by two-and three-dimensional finite element simulations, provides a solid theoretical framework to design metasurfaces for cloaking, wearable optics and next generation of freeform imaging systems

Microresonator defects as sources of drifting cavity solitons

Cavity solitons (CS) are localized structures appearing as single intensity peaks in the homogeneous background of the field emitted by a nonlinear (micro)resonator. In real devices, their position is strongly influenced by the presence of defects in the device structure. In this Letter we show that the interplay between these defects and a phase gradient in the driving field induces the spontaneous formation of a regular sequence of CSs moving in the gradient direction. Hence, defects behave as a device built-in CS source, where the CS generation rate can be set by controlling the system parameters

Microresonator defects as sources of drifting cavity solitons

Cavity solitons (CS) are localized structures appearing as single intensity peaks in the homogeneous background of the field emitted by a nonlinear (micro)resonator. In real devices, their position is strongly influenced by the presence of defects in the device structure. In this Letter we show that the interplay between these defects and a phase gradient in the driving field induces the spontaneous formation of a regular sequence of CSs moving in the gradient direction. Hence, defects behave as a device built-in CS source, where the CS generation rate can be set by controlling the system parameters

Aberration-free ultra-thin flat lenses and axicons at telecom wavelengths based on plasmonic metasurfaces

The concept of optical phase discontinuities is applied to the design and demonstration of aberration-free planar lenses and axicons, comprising a phased array of ultrathin subwavelength spaced optical antennas. The lenses and axicons consist of radial distributions of V-shaped nanoantennas that generate respectively spherical wavefronts and non-diffracting Bessel beams at telecom wavelengths. Simulations are also presented to show that our aberration-free designs are applicable to high numerical aperture lenses such as flat microscope objectives

Enhancing the gain by quantum coherence in terahertz quantum cascade lasers

We propose and study GaAs/AlGaAs terahertz frequency quantum cascade lasers in which mid-infrared radiation is used as a coherent drive for enhancing the terahertz gain

Produire durablement du lait avec des chèvres en forêt méditerranéenne

Depuis, 2008, un Réseau caprin pastoral méditerranéen s’est constitué entre services pastoraux de Provence-Alpes-Côte d’Azur, Languedoc-Roussillon et Corse afin de rénover les références de la valorisation des parcours par les chèvres. En région méditerranéenne, les troupeaux caprins se déploient largement dans la « forêt méditerranéenne », cette mosaïque de taillis, de clairières, de garrigues ou de maquis qui leur fournissent une abondante ressource ligneuse. La contribution des parcours à la ration du troupeau peut alors atteindre jusqu’à 80 % de l’alimentation annuelle : l’élevage caprin transforme, littéralement, la broussaille en fromage. Les suivis réalisés sur une douzaine de fermes de référence montrent qu’un pâturage prudent conduit en gardiennage permet un renouvellement durable de la strate arbustive de 0,4 m à 1,5 m de hauteur fournissant l’essentiel du pâturage des chèvres. A l’inverse, il est possible aussi d’obtenir un impact très fort qui tend à épuiser les arbustes dans un objectif de débroussaillement. Ainsi c’est par un pilotage précis, différencié selon les objectifs, en partenariat avec les gestionnaires de la forêt, que l’élevage caprin peut réinvestir la forêt méditerranéenne, cette fois en accord, et parfois à la demande, des forestiers

Electrically pumped semiconductor laser with monolithic control of circular polarization

We demonstrate surface emission of terahertz (THz) frequency radiation from a monolithic quantum cascade laser with built-in control over the degree of circular polarization by “fishbone” gratings composed of orthogonally oriented aperture antennas. Different grating concepts for circularly polarized emission are introduced along with the presentation of simulations and experimental results. Fifth-order gratings achieve a degree of circular polarization of up to 86% within a 12°-wide core region of their emission lobes in the far field. For devices based on an alternative transverse grating design, degrees of circular polarization as high as 98% are demonstrated for selected far-field regions of the outcoupled THz radiation and within a collection half-angle of about 6°. Potential and limitations of integrated antenna gratings for polarization-controlled emission are discussed