Publications de Ursula Oesterle

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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 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

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.

In this paper, we present an improved version of microcavity light-emitting diodes, relying on the use of a low-index material, aluminum oxide. Our work addresses in particular the injection scheme required by the insulating nature of this oxide. The device we fabricated demonstrated efficiencies up to 28% in air, using only planar technology. In these structures, most of the emission is guided. We further propose to include photonic crystals to extract this guided light. The design of the photonic crystals

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.

Pump-probe measurements in a microcavity containing a quantum well show that a population of circularly polarized (sigma(+)) excitons can completely inhibit the transition to sigma(-) one-exciton states by transferring the oscillator strength to the biexcitonic resonance. With increasing pump intensity the linear exciton-polariton doublet evolves into a triplet polariton structure and finally into a shifted biexciton-polariton doublet. A theoretical model of interacting excitons demonstrates that the crosso

Ursula Oesterle

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

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

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

Toward ultrahigh-efficiency aluminum oxide microcavity light- emitting diodes: Guided mode extraction by photonic crystals

The importance of disorder in very high quality semiconductor microcavities

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

Crossover from exciton to biexciton polaritons in semiconductor microcavities

MBE growth of high finesse microcavities

Models and measurements for the transmission of submicron-width waveguide bends defined in two-dimensional photonic crystals

Nonlinear reflectivity of strongly coupled exciton-photon systems under resonant and non-resonant pumping

Strong coupling regime and cavity-polariton in semiconductor microcavities

In-plane microcavity resonators with two dimensional photonic bandgap mirrors

Collisional broadening of semiconductor microcavity polaritons

Structural and electrooptical characteristics of quantum dots emitting at 1.3 µm on Gallium Arsenide

Coupled guide and cavity in a two-dimensional photonic crystal

Measurement of cavity polariton dispersion curve

Collisional broadening of semiconductor microcavity polaritons

Non linear spatial patterning and coherent scattering effects in cavity-polaritons

Impurity modes in one-dimensional periodic-systems: the transition from photonic band-gaps to microcavities

Cascaded photonic crystal guides and cavities: spectral studies and their impact on integrated optics design