Benoît Marie Joseph Deveaud

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We present a theoretical model of the time-resolved excitonic photoluminescence in quantum wires. We study the role of disorder on the temperature dependence of the photoluminescence lifetime. We find that at low temperature the exciton population is not thermalized in disordered quantum wires and that the lifetime is mainly determined by the localization length of the exciton. However for large localization lengths or high enough temperatures the exciton population thermalizes within its lifetime and the t

The Bogoliubov transformation of a polariton quantum fluid has recently been revealed in the four-wave mixing response of a driven microcavity polariton gas. In this work, we investigate the modifications that the dual nature of microcavity polaritons prod ...

We discuss recent theoretical results on the polariton parametric amplification from semiconductor microcavities in the strong exciton-photon coupling regime. A microscopic treatment of the interacting polariton system leads to a clear description of the phase-matched four-polariton mixing. The results excellently explain the recent observation of giant angle-resonant amplification in pump-probe experiments with co-circularly polarized beams.

We have improved the sensitivity and signal-to-noise ratio of a luminescence upconversion experiment, using a charge-coupled device (CCD) as the detector. We show experimentally and numerically that the bandwidth of a 1-mm-thick beta-barium berate crystal is large enough to take full advantage of the multichannel capabilities of the CCD. The improvement is significant in a standard experiment with a single laser as well as in experiments with resonant excitation that use two synchronized femtosecond pulse s

We present the optical tomography of the probability density of quasiparticles, the microcavity polaritons, confined in three dimensions by cylindrical traps. Collecting the photoluminescence emitted by the quasimodes under continuous nonresonant laser exc ...

We have performed low-density (< 10(5) cm(-1)) time-resolved photoluminescence experiments that probe the relaxation of photo-excited carriers in a quantum wire. Our results show that carrier-carrier collisions are dominant at very short times both for intra- and for inter-subband scattering as only expected if non-Markovian effects are taken into account. (C) 1999 Elsevier Science B.V. All rights reserved.

Femtosecond luminescence measurements combined with pump-probe experiments using selective excitation of either free carriers or excitons have been performed. The time-resolved luminescence spectra show a striking disparity compared with recently published theoretical models. Large differences in the pump-probe spectra are observed for resonant and non-resonant (continuum) pumping. The origin of these differences is discussed.

The intramol. energy relaxation processes of UV-excited C60 mols. embedded in Ar crystals were studied by picosecond fluorescence studies and femtosecond pump-probe absorption spectroscopy. The various internal energy relaxation steps are clearly identified. The importance of intramol. energy relaxation processes in solid C60 films is underlined. [on SciFinder (R)]

We investigate a semiconductor microcavity containing a quantum well, a sample of exceptional quality. We observe a four-wave mixing response which resembles that of an inhomogeneously broadened exciton system, while the linear transmission measurements are affected by the homogeneous part of the broadening and have a completely different decay time. We show that the four-wave mixing response cannot be calculated using the excitonic parameters (linewidth and relaxation time) extracted from the linear transm

A novel method of controlling light absorption by exciton-polaritons is presented. The coherent light-induced coupling of excitons in multiple quantum well Bragg structures is exploited to sup press dramatically the absorption. Our results show that excitonic light absorption is not an intrinsic property of excitons but rather an extrinsic effect that occurs when the excitons dephase.

Excitons and trions in a CdTe modulation-doped quantum well are investigated by picosecond three-pulse four-wave mixing experiments as a function of temperature in the low-density regime. We show that trions are mobile for high enough temperatures. The diffusivity of trions and excitons increases with temperature but, like their mobilities, is limited by acoustic-phonon scattering. Consistently, studying the decay of the interband coherence reveals an increase of the homogeneous broadening as the temperatur

A brief review is given of optical experiments related to the creation and recombination of charged excitons. The fundamental parameters of these states are discussed. This includes their energies, optical transition probabilities, and characteristic times of their formation, thermalisation, and decay. A model of free three-particle charged exciton is shown to describe correctly the results of many experiments. The applicability range of the model is limited by many body effects at higher carrier concentrat

Electron transfer from GaAs wells (Gamma wavefunctions) to AlAs barriers (X wavefunctions) in GaAs / AlAs type II superlattices has been studied by time resolved luminescence with femtosecond resolution. Transfer times can be as short as 140 fs for narrow wells and as long as 25 ps for the widest wells. They do not depend appreciably on the barrier thickness. We discuss the possible contribution to the transfer mechanism of state mixing, intervalley scattering and Frolich interaction. Our measurement favors

Ultrafast pump-probe measurements evidence the dynamical Stark splitting in the exciton absorption spectrum of a single semiconductor quantum well. The intensity of the Stark sidebands in the spectrum is comparable to the linear absorption and their separation scales as the pump field amplitude. In the time domain the Rabi oscillations are observed. The semiconductor Bloch equations solved in the Hartree-Fock approximation demonstrate that the coherent exciton-light coupling dominates over the many-body dep

We engineer a semiconductor microcavity through an appropriate choice of geometry and materials in order to maximise the exciton-photon coupling. The polaritonic nonlinearities in such devices survive at high temperatures and high excitation densities. We measure parametric polariton amplification up to 220 K in CdTe microcavities and up to 120 K in GaAs ones. The amplification is also outstanding, reaching as much as 5000 at low temperature. The experimental observations suggest that the operating temperat

Using femtosecond resonant luminescence, we have measured the intersubband scattering rate of electrons in wide GaAs quantum wells at very low excitation densities. Even when the spacing be tween 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

We report on time-resolved photoluminescence studies of tunnelling in a system of asymmetric double quantum wells (QWs). We employ a structure with a semimagnetic QW to align carrier spins and with excess concentration of electrons to provide a sensitive tool for studying the heavy hole dynamics. We prove the existence of hole tunnelling and demonstrate an efficient spin transfer in the process. A semi-empirical model describes qualitatively the experimental findings.

Spatio-time-resolvedcathodoluminescence (STRCL) spectroscopy isimplemented to assess the local carrier dynamics in a 70 nm-thick, very low threading dislocation (TD) density, pseudomorphic m-plane In GaN epilayer grown on a freestanding GaN substrate by me ...

The interaction between coherent polaritons and incoherent excitons plays an important role in polariton physics. Using resonant pump-probe spectroscopy with selective excitation of single polariton branches, we investigate the different dephasing mechanis ...

We present a low-temperature time-resolved cathodoluminescence study on (In,Ga)N/GaN quantum wells grown on the (11-22) facets of non-coalesced ELO-GaN. Taking advantage of the quantum confined Stark effect, such structures have been proposed as promising ...

Benoît Marie Joseph Deveaud

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Temperature dependence of the photoluminescence lifetime in disordered quantum wires

Four-wave mixing excitations in a dissipative polariton quantum fluid

Giant angle-resonant polariton amplification

Improving the signal-to-noise ratio of femtosecond luminescence upconversion by multichannel detection

Probability density optical tomography of confined quasiparticles in a semiconductor microcavity

Intrasubband and intersubband scattering in semiconductor quantum wires

Is luminescence from quantum wells due to excitons?

Picosecond and femtosecond studies of the energy redistribution in matrix-isolated C60 molecules

The importance of disorder in very high quality semiconductor microcavities

Is light absorption by excitons in quantum wells an intrinsic process?

Diffusion, localization, and dephasing of trions and excitons in CdTe quantum wells

Optical studies of charged excitons in II-VI semiconductor quantum wells

Ultrafast electron transfer in type II GaAs/AlAs superlattices by femtosecond luminescence

Direct observation of the excitonic ac Stark splitting in a quantum well

Towards a room temperature polariton amplifier

Efficient intersubband scattering via carrier-carrier interaction

Tunnelling of spin-polarized holes in asymmetric double quantum well structures

Implementation of spatio-time-resolved cathodoluminescence spectroscopy for studying local carrier dynamics in a low dislocation density m-plane InGaN epilayer grown on a freestanding GaN substrate

Coherent and incoherent aspects of polariton dynamics in semiconductor microcavities

Time-resolved cathodoluminescence on polychromatic light emitting (In,Ga)N quantum wells grown on (11-22) GaN facets