Benoît Marie Joseph Deveaud

Chattez avec Graph Search

Posez n’importe quelle question sur les cours, conférences, exercices, recherches, actualités, etc. de l’EPFL ou essayez les exemples de questions ci-dessous.

AVERTISSEMENT : Le chatbot Graph n'est pas programmé pour fournir des réponses explicites ou catégoriques à vos questions. Il transforme plutôt vos questions en demandes API qui sont distribuées aux différents services informatiques officiellement administrés par l'EPFL. Son but est uniquement de collecter et de recommander des références pertinentes à des contenus que vous pouvez explorer pour vous aider à répondre à vos questions.

We report femtosecond pump and probe experiments in a semiconductor microcavity containing quantum wells. At high pump fields, the exciton-polariton Rabi doublet changes into a triplet structure. The triplet splitting increases as the square root of the input intensity. The transmitted probe intensity is modulated with the corresponding frequency Versus pump-probe delay. The experimental results are discussed in terms of Mollow spectra of a saturated transition of a two-level system.

We report on a distance control system for low-temperature scanning near-field optical microscopy, based on quartz tuning fork as shear force sensor. By means of a particular tuning fork optical fiber configuration, the sensor is electrically dithered by an applied alternate voltage, without any supplementary driving piezo, as done so far. The sensitivity in the approach direction is 0.2 nm, and quality factors up to 2850 have been reached. No electronic components are needed close to the sensor, allowing t

The coherent optical response of high quality microcavities containing quantum wells is investigated. The dynamics of the ac Stark effect is investigated by degenerate pump-probe experiments, by exciting the quantum well excitons at various intensities and detunings. The evolution from a simple dynamical excitonic Stark shift to a splitting is dearly observed, even when the excitation is degenerate with the continuum states. The experimental results agree well with the predictions of a theoretical model bas

A dramatic suppression of the absorption of light by exciton polaritons is observed after resonant excitation of the polaritonic modes in a multiple quantum well Bragg structure. Time-resolved reflectivity measurements confirm that this is due to the formation of a dominant superradiant polariton mode created by the light-induced coupling of excitons in different quantum wells that suppress absorption. The stability of the superradiant mode is demonstrated at high excitation powers and at temperatures of up

We report novel oscillator strength transfer phenomena induced by the exciton-exciton correlation. A high quality semiconductor microcavity is resonantly excited by intense circularly polarised sigma(+) pump pulses (100 fs long) and probed at different delays by weak counter-polarised sigma(-) test pulses. We show that the presence of sigma(+) excitons can completely inhibit the creation of sigma(-) excitons. With increasing sigma(+) exciton density the oscillator strength of the a- transition is transferre

We experimentally demonstrate a technique for the generation of optical beams carrying orbital angular momentum using a planar semiconductor microcavity. Despite being isotropic systems with no structural gyrotropy, semiconductor microcavities, because of ...

A microscopic theory is presented for the giant amplification from microcavities in the strong exciton-photon coupling regime, providing excellent agreement with recent angle-resolved pump-probe experiments. The analytical and numerical solutions give insight into the physics of the polariton parametric amplifier. The coherent gain, due to polariton four-wave-mixing, has a threshold dependence on the pump power and is spectrally blueshifted from the lower polariton energy. The gain shift does not depend on

We show a double path mechanism for the formation of charged excitons (trions); they are formed through bi- and trimolecular processes. This directly implies that both negatively and positively charged excitons coexist in a quantum well, even in the absenc ...

Using femtosecond resonant luminescence, we have measured the intersubband scattering fare of electrons in wide GaAs quantum wells at very low excitation densities. Even when the spacing between the first two electron subbands is smaller than the LO phonon energy, we observe that intersubband scattering is a subpicosecond process, much faster than previously measured or anticipated. Our experimental results are in perfect agreement with Monte Carlo calculations, which show that carrier-carrier interaction i

We have measured the ultrafast resonant Rayleigh scattering from quantum-well excitons using Fourier-transform spectral interferometry. The experiment simultaneously measures a statistically significant number of speckles with 100 fs temporal resolution. We show that theories based on ensemble averaging can he compared directly with the experimental resonant Rayleigh scattering dynamics.

The emission properties of self-assembled InAs quantum dots (QDs) and lattice-matched GaInNAs quantum wells (QWs) emitting around 1.3 mum were investigated by temperature-dependent and time-resolved photoluminescence (PL). The QDs have much higher PL efficiency at low excitation, but saturate faster as the excitation is increased, due to the lower density of states. Lifetime measurements show that nonradiative recombination plays a more important role in the GaInNAs QW than in QDs. (C) 2002 American Institu

We investigate the spin relaxation of negatively charged excitons in modulation-doped CdTe quantum wells by time-resolved photoluminescence. The charged exciton spin flip process is found to be very sensitive to the excitation energy but not to a change of electron concentration. We exclude the Bir-Aronov-Pikus mechanism, which is based on the exchange interaction, as responsible for the X- spin flip.

We study the coherent optical response of a very high-finesse microcavity with a single quantum well by means of degenerate subpicosecond pump-probe spectroscopy. The dynamics of the ac Stark effect versus Pump intensity is investigated upon tuning the empty-cavity;mode-below and above the exciton transition energy, at the exciton continuum onset. The evolution from a simple dynamical excitonic shift to a dynamical splitting is clearly observed in both eases. The qualitative, agreement with numerical calcul

We report on the observation of spontaneous coherent oscillations in a microcavity polariton bosonic Josephson junction. Condensation of exciton polaritons here takes place under incoherent excitation in a double potential well naturally formed in the disorder. Coherent oscillations set on at an excitation power well above the condensation threshold. The time resolved population and phase dynamics reveal the analogy with the ac Josephson effect. A theoretical two-mode model describes the observed effects, e

A dramatic suppression of the light absorption by exciton-polaritons is observed after resonant excitation of the polaritonic modes in a multiple quantum well Bragg structure. We demonstrate that this is due to the formation of a dominant superradiant polariton mode. The stability of the superradiant mode is demonstrated at high excitation powers and at temperatures of up to 180 K. (C) 1999 Elsevier Science B.V. All rights reserved.

Using luminescence upconversion with 100 fs resolution, we have investigated the intersubband scattering of electrons in GaAs quantum wells (QWs). The energy separations between the first and second confined electron subband (E(12)) were more or less than the LO phonon energy (E(LO)) In narrow QWs (E(12) > E(LO)) the intrinsic LO phonon scattering rate is found to be 1.6 x 10(12) s(-1). A Monte Carlo simulation allows us to reproduce the experimental data with high accuracy. In wide QWs (E(12) < E(LO)) We f

Polaritons are an odd cross-breed of a particle, half-matter, half-light. They could offer an abundant crop of new and improved optoelectronic devices — a promise already being fulfilled. ...

The influence of magnetic field on confined exciton-polariton modes inside a semiconductor microcavity is discussed. The three-dimensional confinement for exciton-polaritons is achieved by the mesa structures confining the photonic part of polaritons. We o ...

We study the coherence and density modulation of a nonequilibrium exciton-polariton condensate in a one-dimensional valley with disorder. By means of interferometric measurements we evidence a modulation of the ﬁrst-order coherence function and we relate i ...

In this work, we report on the first realization of multi-valued spin switching in the solid-state. We investigate the physics of spinor bistability with microcavity polaritons in a trap. Spinor interactions lead to special bistability regimes with decoupled thresholds for spin-up and spin-down polaritons. This allows us to establish state-of-the-art spin switching operations. We evidence polarization hysteresis and determine appropriate conditions to achieve spin multistability. For a given excitation cond

Benoît Marie Joseph Deveaud

Chattez avec Graph Search

Strongly driven semiconductor microcavities: From the polariton doublet to an AC Stark triplet

Ultra stable tuning fork sensor for low-temperature near-field spectroscopy

The microcavity AC Stark triplet: Excitation in the exciton continuum

Suppression of exciton-polariton light absorption in multiple quantum well Bragg structures

Crossover from exciton to biexciton cavity polaritons

Spin-to-orbital angular momentum conversion in semiconductor microcavities

Theory of the angle-resonant polariton amplifier

Dynamics of trion formation in GaAs quantum wells

Efficient intersubband scattering via carrier-carrier interaction in quantum wells

Speckle-averaged resonant Rayleigh scattering from quantum-well excitons

Comparison of radiative properties of InAs quantum dots and GaInNAs quantum wells emitting around 1.3 mu m

Spin relaxation of negatively charged excitons in CdTe quantum wells

Direct observation of an ac Stark splitting in semiconductor microcavities excited above the continuum onset

Coherent Oscillations in an Exciton-Polariton Josephson Junction

Suppression of exciton-polariton light absorption in multiple quantum well Bragg structures

Intersubband scattering rates in GaAs quantum wells under selective and resonant excitation, measured by femtosecond luminescence

Solid-state physics - Polaritronics in view

Magnetic Field Induced Redistribution of Exciton-Polariton Density on Confined Modes

Polariton Condensation in a One-Dimensional Disordered Potential

Multi-Valued Spin Switch in a Semiconductor Microcavity