Absorption enhancement in photonic crystal thin films by pseudo disordered perturbations

The effects resulting from the introduction of a controlled perturbation in a single pattern membrane on its absorption are first studied and then analyzed on the basis of band folding considerations. The interest of this approach for photovoltaic applications is finally demonstrated by overcoming the integrated absorption of an optimized single pattern membrane through the introduction of a proper pseudo disordered perturbation.Comment: MRS Fall Meeting 2013, Boston : United States (2013

Absorption control in pseudodisordered photonic-crystal thin film

The positive effects of various perturbations introduced in a bidimensional photonic-crystal patterned membrane on its integrated absorption are investigated numerically and theoretically. Two phenomena responsible for the enhanced absorption observed are identified: an increase of the spectral density of modes, obtained thanks to folding mechanisms in the reciprocal lattice, and a better coupling of the modes with the incident light. By introducing a proper pseudodisordered pattern, we show that those two effects can be exploited so as to overcome the integrated absorption obtained for an optimized and single pattern unit cell photonic crystal

Near-field spectroscopy of low-loss waveguide integrated microcavities

International audienceA scanning near-field spectroscopy method is used to observe loss reduction and Q-factor enhancement due to transverse-mode profile matching within photonic-crystal microcavities. Near-field measurements performed directly on cavity modes are compared with three-dimensional calculations and quantitative agreement is observed. (c) 2006 American Institute of Physics

Interaction en champ proche entre une sonde nanométrique et le champ de composants à cristal photonique:<br />- interaction faible, microscopie spatialement hautement résolue<br />- interaction forte, contrôle des propriétés du composant.

With the improvement of fabrication techniques, the nanophotonics and more especially the photonics crystals which are periodic structure at the Wavelength scale have been recently developed. In this work, by using a scanning near-field optical microscope, we study such components. Firslty, we use the local probe to visualize the light distribution inside photonic crystal microcavities etched into semiconductor III/V. We focus us on the explanation of the near-field maps formation and on the probe influence on these maps. Thus, we have visualize degeneracy splitting of optical cavity modes and clearly observed in near-field cavity modes which were not visible in far-field. Moreover, in the case of Bloch mode cavities, we have also experimentally determined the dispersion curves of the photonic crystal. secondly, we use the local probe to control the nanoresonator properties. The nanoresonators consist in high Q small v photonic crystal cavity. In this case, we study theoretically as well as experimentally the interaction between the local probe and the nanocavity. Thus, we have mapped this interaction in the collection mode as well as in the interaction mode. Moreover, we have proposed some near-field opto-mechanical systems.Grâce à l'amélioration des technologies de fabrication, la nanophotonique, et plus particulièrement les cristaux photoniques (structures périodiques à l'échelle de la longueur d'onde) ont connu un fort développement récemment. Dans ce manuscrit, nous utilisons la microscopie en champ proche optique pour étudier de tels composants.Dans la première partie de ce travail, nous utilisons la sonde locale du microscope pour imager la distribution de la lumière au sein de cavités à cristal photonique réalisées dans un semiconducteur III/V. Nous nous sommes intéressés à expliquer la formation des images optiques en champ proche et à visualiser l'influence de la sonde sur ces images. Ainsi, nous avons pu observer des levées de dégénérescence de mode de cavité et des modes de cavité invisibles en champ lointain. Enfin, pour des cavités à- mode de Bloch, nous avons pu déterminer expérimentalement les courbes de dispersion du cristal photonique.Dans la seconde partie de ce travail, nous utilisons la sonde locale du microscope pour contrôler les propriétés de nanorésonateur formés à partir de cavité à cristal photonique à faible volume modal et grand facteur de qualité. Nous avons étudié l'interaction entre la sonde et le résonateur d'un point de vue théorique et expérimental. Aussi, nous avons pu montrer la complémentarité d'une mesure en mode interaction et en mode collection. De plus, nous avons proposé des fonctionnalités opto-mécaniques en champ proche optique

Binary coded patterns for photon control using necklace problem concept

International audiencePseudo-disordered structures enable additional design freedom for photon management. However, the optimization and interpretation is challenging when the large number of degrees of freedom encounters computationally intensive electromagnetic simulation method. Here we propose a novel one-dimensional multi-periodic pattern generation method to help us squeeze the disorder design space before performing rigorous calculation, by making use of the periodic attribute of the pattern. Consequently, thanks to the pre-filtered design space, it typically relieves us from computational burden and enables us to ‘globally’ optimize and study pseudo-disordered patterns. As an example, we show how this approach can be used to comprehensively optimize and systematically analyze generated disorder for broadband light trapping in thin film

Quasi-cylindrical waves at the interface of a semiconductor device

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Optical quasicylindrical waves at dielectric interfaces

Much effort has been recently devoted to the study of the electromagnetic field launched on a metal-dielectric interface by one-dimensional (1D) subwavelength indentations. In this work, we consider the wave launched on a semiconductor surface that does not support any surface modes, in contrast to the metallic case. Through analytical calculations performed for polarized 2D Dirac line sources, we show that the waves launched by the two orthogonal polarizations (parallel and perpendicular to the surface) have approximately the same form, differing only in phase and magnitude. This finding implies that the wave launched on the surface by an arbitrary subwavelength indentation under an arbitrary illumination, either at grazing, normal, or oblique incidence, is always the same and possesses universal characteristics.We further observe this wave on a silicon substrate with a near-field probe. Through fitting with a simple model, the measured field is found to exhibit characteristics that are reminiscent of quasicylindrical waves on metal surfaces.NANOstructured active MAGneto-plasmonic MAterial

Quasi-cylindrical waves at the interface of a semiconductor device

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ABSORPTION ENHANCEMENT IN DISORDERED PHOTONIC CRYSTALS: A PHOTONICS POINT OF VIEW

International audienceTHis paper explain within a photonic point of view what is the origin and the effect of pseudo periodic structure in photonic crystal for absorption