Ultimate fast optical switching of a planar microcavity in the telecom wavelength range

We have studied a GaAs-AlAs planar microcavity with a resonance near 1300 nm in the telecom range by ultrafast pump-probe reflectivity. By the judicious choice of pump frequency, we observe a ultimate fast and reversible decrease of the resonance frequency by more than half a linewidth due to the instantaneous electronic Kerr effect. The switch-on and switch-off? of the cavity is only limited by the cavity storage time of ?tcav = 0.3ps and not by intrinsic material parameters. Our results pave the way to supra-THz switching rates for on-chip data modulation and real-time cavity quantum electrodynamics.Comment: 3 pages, 3 figure

Genetic parameters for milk, fat and protein yields in Murrah buffaloes (Bubalus bubalis Artiodactyla, Bovidae)

The objective of the present study was to estimate genetic parameters for test-day milk, fat and protein yields and 305-day-yields in Murrah buffaloes. 4,757 complete lactations of Murrah buffaloes were analyzed. Co-variance components were estimated by the restricted maximum likelihood method. The models included additive direct genetic and permanent environmental effects as random effects, and the fixed effects of contemporary group, milking number and age of the cow at calving as linear and quadratic covariables. Contemporary groups were defined by herd-year-month of test for test-day yields and by herd-year-season of calving for 305-day yields. The heritability estimates obtained by two-trait analysis ranged from 0.15 to 0.24 for milk, 0.16 to 0.23 for protein and 0.13 to 0.22 for fat, yields. Genetic and phenotypic correlations were all positive. The observed population additive genetic variation indicated that selection might be an effective tool in changing population means in milk, fat and protein yields

Contrôle de l'émission spontanée de boîtes quantiques semiconductrices insérées dans des micro-structures à confinement optique originales

This study deals with the control of spontaneous emission, InAs quantum dot emitters, confined via original microstructures: GaAs photonic wires and micropillars with GaAs/AlAs Bragg mirrors. We present a higly efficient single-photon source based on a photonic wire. Correlation mesurements performed on a single quantum dot inserted in a photonic wire led to a pure and high broadband single-photon generation. The optimization of this geometry including an original mirror at the wire bottom and a taper at its top demonstrated a record efficiency of 70%. In addition, the systematic lifetime study of single quantum dots underlined the ability to observe a high inhibition of spontaneous emission in the leaky modes with this geometry. In the last part of this PhD Thesis, we show the laser effect in whispering gallery mode micropillars. Those modes have an almost stable behaviour in terms of wavelengh and a spectral narrowing maintained up to power corresponding to 7 times the laser threshold. This result confirms a better thermal stability of micropillars compared to microdisks, a geometry usually used to observe the whispering gallery modes.Ce travail de thèse aborde le contrôle de l'émission spontanée d'émetteurs, ici des boîtes quantiques d'InAs, confinées via des microstructures originales: des fils photoniques GaAs et des micropiliers à miroirs de Bragg GaAs/AlAs. Ainsi, nous présentons une source de photons uniques de très haute efficacité à fil photonique. Les mesures de corrélation réalisées sur une boîte quantique unique insérée dans un fil photonique a permis de montrer la génération très propre et large bande de photons uniques. C'est l'optimisation de cette géométrie incluant un miroir original au pied du fil et la présence d'une pointe de forme conique à son extrémité, qui a permis d'obtenir une efficacité record de 70%. De plus, l'étude systématique de temps de vie de boîtes quantiques uniques montre la possibilité d'observer avec cette géométrie une forte inhibition de l'émission dans les modes non-guidés. La dernière partie de ce manuscrit met en évidence l'effet laser dans des micropiliers à modes de galerie. Ces modes de galerie présentent un comportement relativement stable en longueurs d'ondes ainsi qu'un affinement spectral se maintenant jusqu'à sept fois le seuil laser. Ce résultat confirme une meilleure stabilité thermique des micropiliers par rapport à la géométrie habituellement utilisée pour observer les modes de galerie: les microdisques

Ultimate fast optical switching of a semiconductor photonic microcavity

We present ultrafast pump-probe reflectivity measurements on semiconductor microcavities with a resonance at telecom wavelengths. We observe an ultimate fast red shift and recovery of the cavity resonance due to the instantaneous electronic Kerr effect

Ultimate fast optical switching of a semiconductor photonic microcavity

We present ultrafast pump-probe reflectivity measurements on semiconductor microcavities with a resonance at telecom wavelengths. We observe an ultimate fast red shift and recovery of the cavity resonance due to the instantaneous electronic Kerr effect

Spatially resolved modes in GaAs/AlAs micropillar resonators

We present broadband reflectivity measurements on micropillars, resolving distinct modes inside the cavity resonance. We observe that the spectral mode position and spacing strongly depend on both pillar diameter and illumination position

A highly efficient single-photon source based on a quantum dot in a photonic nanowire

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