Publications de Stefan Kundermann

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This thesis presents the coherence properties of polaritons in semiconductor microcavities. Semiconductor microcavities are microstructures in which the exciton ground state of a semiconductor quantum well is coupled to a photonic mode of a microresonator. ...

Microcavity exciton polaritons, the fundamental optical excitations of semiconductor microcavities with quantum wells inside, have been proposed as promising candidates for observing stimulated scattering, condensation and other phenomena related to the bosonic nature of excitons. Having a light mass, quantum degeneracy of polaritons can be reached at low densities and high temperatures. But the radiative time of polaritons is very short (in the picosecond range) and usually prevents an efficient thermaliza

In this review, we present a comprehensive set of experimental results on microcavity-polariton Bose-Einstein Condensation (BEC), obtained within a close collaboration between Institut Neel, Grenoble, France and EPFL, Lausanne, Switzerland. First, we recal ...

Modifying the photonic environment of a semiconductor quantum well by embedding it in a high-reflectivity microcavity gives rise to new fundamental optical excitations, half-quantum well excitons, half-photons. These particles, called polaritons, have a light mass, as cavity photons, meaning that they have a large De Broglie wavelength. On the other hand, polaritons, like excitons, are subject to Coulomb interaction, a feature generating strong optical nonlinearities. Such properties favour quantum degenera

Earth-like planets, dark energy and variability of fundamental physical constants can be discovered by observing wavelength shifts in the optical spectra of astronomical objects(1-5). These wavelength shifts are so tiny that exquisitely accurate and precis ...

Cavity polaritons, the elementary optical excitations of semiconductor microcavities, may be understood as a superposition of excitons and cavity photons(1). Owing to their composite nature, these bosonic particles have a distinct optical response, at the same time very fast and highly nonlinear. Very efficient light amplification due to polariton-polariton parametric scattering has recently been reported in semiconductor microcavities at liquid-helium temperatures(2-11). Here we demonstrate polariton param

An investigation of the parametric amplification and its coherent control in a semiconductor micro-cavity is presented. The time and angle resolved pump and probe experiments show that several ps after pumping parametric scattering is still phase coherent. The experimental data are in qualitative agreement with the numerical data obtained from a relatively simple theoretical model based on three polarisation components, pump, probe, and idler. This model also predicts that under particular circumstances, th

In a pump-probe experiment, we have been able to control, with phase-locked probe pulses, the ultrafast nonlinear optical emission of a semiconductor microcavity, arising from polariton parametric amplification. This evidences the coherence of the polariton population near k = 0, even for delays much longer than the pulse width. The control of a large population at k = 0 is possible although the probe pulses are much weaker than the large polarization they control. With rising pump power the dynamics of the

In this work we present the coherent control of polariton parametric scattering with weak phase locked probe pulses. It is demonstrated that the signal emission arising from the parametric scattering is completely coherent for moderate excitation power, whereas at high pump density the dynamics appears less coherent due to the depletion of the pump polariton reservoir. It is furthermore demonstrated that the phase of the probe pulses controls the emission from signal, pump, and idler at the same time.

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

Stefan Kundermann

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Coherence properties of microcavity polaritons : from parametric scattering to Bose-Einstein condensation

Towards a room-temperature polariton amplifier

Polariton amplification in semiconductor microcavities

Exciton-polariton Bose-Einstein condensation: advances and issues

Polariton parametric amplification in semiconductor microcavities

A microphotonic astrocomb

High-temperature ultrafast polariton parametric amplification in semiconductor microcavities

Quantum kinetics of parametric polariton scattering in microcavities

Coherent control of polariton parametric scattering in semiconductor microcavities

Coherence properties of polaritons in semiconductor microcavities

Towards a room temperature polariton amplifier