Tamm plasmon Photonic Crystals : from Bandgap Engineering to Defect Cavity

We report for the first time the bandgap engineering of Tamm plasmon photonic crystals - Tamm plasmon structures of which the metalic layer is periodically patterned into lattice of subwavelength period. By adopting a double period design, we evidenced experimentally a complete photonic bandgap up to $150\,nm$ in the telecom range. Moreover, such design offers a great flexibility to tailor on-demand, and independently, the band-gap size from $30\,nm$ to $150\,nm$ and its spectral position within $50\,nm$. Finally, by implementing a defect cavity within the Tamm plasmon photonic crystal, an ultimate cavity of $1.6\mu m$ supporting a single highly confined Tamm mode is experimentally demonstrated. All experimental results are in perfect agreement with numerical calculations. Our results suggests the possibility to engineer novel band dispersion with surface modes of hybrid metalic/dielectric structures, thus open the way to Tamm plasmon towards applications in topological photonics, metamaterials and parity symmetry physics

Backscattering suppression in supersonic 1D polariton condensates

We investigate the effects of disorder on the propagation of one-dimensional polariton condensates in semiconductor microcavities. We observe a strong suppression of the backscattering produced by the imperfections of the structure when increasing the condensate density. This suppression occurs in the supersonic regime and is simultaneous to the onset of parametric instabilities which enable the "hopping" of the condensate through the disorder. Our results evidence a new mechanism for the frictionless flow of polaritons at high speeds.Comment: 5 pages, 3 figure

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe

Micro-nano structures à base de cristaux photoniques pour le contrôle 3D de la lumière

3D control of light can be realized, at the wavelength scale, in photonic integrated circuits. The building block used in this study is the photonic crystal slab, which enables an in-plane as well as out-of-plane control of light, thanks to its peculiar dispersion properties. Especially at the gamma point of the dispersion curve, slow Bloch modes can be used to realize vertical emitting devices. In this study, we focus on photonic crystals based on micropillar lattices, as an alternative to classical hole lattices. Besides, micropillar lattices can be seen as a new platform for sensing applications and microfluidic circuits. Indeed, fluids can flow through the micropillar. First, we will describe some devices which operate at Gamma point. We will show that, for the first time, the use of highly resonant Bloch modes allow the experimental demonstration of vertical emitting microlasers. Weakly resonant Bloch modes can be used to realize photonic crystal mirrors and Fabry-Perot microcavities constituted only by photonic crystal mirrors. High quality factors (>10000) obtained in such microcavities allow the fabrication of a new type of VCSEL. In a second part, we will focus on the communication between the photonic crystal devices and the surroundings. First, we will explain how the far field pattern can be optimized. At last, we will study the coupling between a photonic crystal structure and a silicon strip waveguide. We show that simulation results give high coupling efficiency (>90%). The samples, fabricated at the LETI-CEA (Grenoble), are still under process.Le contrôle 3D de la lumière est réalisé, à l'échelle de la longueur d'onde, dans des circuits photoniques intégrés. La brique élémentaire choisie dans cette étude est le cristal photonique (CP) membranaire qui, par ses propriétés de dispersion, permet un contrôle de la lumière à la fois dans le plan (optique guidée) et hors du plan (dispositifs adressables par la surface). En particulier, l'exploitation de modes de Bloch situés au point Gamma de la courbe de dispersion (k//=0) permet l'émission de la lumière dans la direction verticale. Dans cette étude, nous nous sommes focalisés sur des cristaux photoniques à réseaux de micropiliers, comme alternative aux réseaux de trous, mais également en envisageant la possibilité d'intégrer ces structures dans des systèmes microfluidiques, les fluides ayant la capacité de circuler au travers des réseaux de piliers. Nous décrirons dans une première partie, des dispositifs à CP à émission par la surface. Nous démontrerons, pour la première fois, que l'utilisation de modes fortement résonants permet de réaliser des microlasers à réseaux de piliers en InP. Les modes faiblement résonants peuvent être utilisés pour la réalisation de miroirs à CP et de microcavités Fabry-Pérot constituées uniquement de tels miroirs. Les facteurs de qualité obtenus (>10000) rendent possible la fabrication de nouveaux types de VCSEL. Dans une seconde partie, nous nous intéresserons à la problématique de l'intégration de ces dispositifs dans un circuit photonique 3D. Tout d'abord, nous expliquerons comment il est possible d'optimisation le diagramme de rayonnement des composants. Ensuite, nous étudierons le couplage de dispositifs à cristaux photoniques avec un ou deux guides d'onde ruban en silicium. De fortes efficacités de couplage sont obtenues en simulation FDTD 3D (95%). Ces dispositifs en cours de fabrication en collaboration avec le LETI-CEA de Grenoble permettront de démontrer expérimentalement ce couplage

Controlled Multi-Wavelength Emission in Full CMOS Compatible Micro-Lasers for on Chip Interconnections

We report on a system to control the emitted wavelength of a laser independently from its pump conditions. To illustrate the concept, it is applied to III-V microdisk lasers fabricated on a CMOS pilot line for application to multicolored optical interconnections. Two different control systems are experimentally studied. The first one requires two coupling areas between the resonator and its coupled waveguide while the second solution is based on a photonic crystal mirror and a single coupling area. In both cases, the independent tuning of their emission from the pump conditions is demonstrated with a very high compacity. A controlled multimode emission in microdisk lasers is obtained for the first time

Spontaneous formation of a polariton condensate in a planar GaAs microcavity

We report on polariton condensation in a planar GaAs microcavity under nonresonant optical excitation. Angularly resolved photoluminescence measurements demonstrate polariton condensation for temperature up to 40 K. Numerical simulations using Boltzmann equations give an overall description of the observed condensation for various detunings and temperatures. This model highlights the importance of the polariton relaxation rate as compared to the polariton decay for condensation to occur on the lowest energy polariton states

Supplementary document for How many supercells are required to achieve unconventional light confinement effects in moiré photonic lattices? - 6691411.pdf

suplemental documen

Metallo-dielectric metasurfaces for thermal emission with controlled spectral bandwidth and angular aperture

International audienceWe introduce thermal metallo-dielectric metasurfaces as mid IR sources. The emitter is a lossy metal. The spectral and angular emission is controlled using a periodic array of high refractive dielectric resonators. We introduce a design that allows to control independently the emission bandwidth and the angular aperture while ensuring a large emissivity. To validate the concept, we fabricated and characterized a metasurface, showing a good agreement with the theory