Magnetic field tuning of exciton-polaritons in a semiconductor microcavity

Benoît Marie Joseph Deveaud, François Morier-Genoud, Barbara Pietka
American Physical Society, 2015
Article

We detail the influence of a magnetic field on exciton-polaritons inside a semiconductor microcavity. Magnetic field can be used as a tuning parameter for exciton and photon resonances. We discuss the change of the exciton energy, the oscillator strength, and redistribution of the polariton density along the dispersion curves due to the magnetically induced detuning. We have observed that field-induced shrinkage of the exciton wave function has a direct influence not only on the exciton oscillator strength, which is observed to increase with the magnetic field, but also on the polariton linewidth. We discuss the effect of the Zeeman splitting on polaritons the magnitude of which changes with the exciton Hopfield coefficient and can be modeled by independent coupling of the two spin components of excitons with cavity photons.

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Benoît Marie Joseph Deveaud, François Morier-Genoud, Barbara Pietka
American Physical Society, 2015
Article

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https://infoscience.epfl.ch/record/207336?ln=fr

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

Benoît Marie Joseph Deveaud, François Morier-Genoud, Gaël Nardin, Barbara Pietka

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 observe a strong increase of the polariton emission intensity and we argue that this effect is due to the change of the oscillator strength of the excitonic component of polaritons and the change of the excitonic content in polariton state as the magnetic field increases.

Polish Acad Sciences Inst Physics2012

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High-temperature ultrafast polariton parametric amplification in semiconductor microcavities

Cristiano Ciuti, Benoît Marie Joseph Deveaud, Stefan Kundermann, Michele Saba

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 parametric amplification up to 120 K in GaAlAs-based microcavities and up to 220 K in CdTe-based microcavities. We show that the cut-off temperature for the amplification is ultimately determined by the binding energy of the exciton. A 5-mum-thick planar microcavity can amplify a weak light pulse more than 5,000 times. The effective gain coefficient of an equivalent homogeneous medium would be 10(7) cm(-1). The subpicosecond duration and high efficiency of the amplification could be exploited for high-repetition all-optical microscopic switches and amplifiers. 10(5) polaritons occupy the same quantum state during the amplification, realizing a dynamical condensate of strongly interacting bosons which can be studied at high temperature.

2001

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Polariton parametric amplification in semiconductor microcavities

Cristiano Ciuti, Benoît Marie Joseph Deveaud, Stefan Kundermann, Michele Saba

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 degeneracy and collective phenomena related to the bosonic statistics of polaritons. We review experiments on stimulated scattering of polaritons. In particular we concentrate on the resonant excitation of polaritons somewhere on the dispersion curve and the stimulation of their scattering into the fundamental state by means of an optical probe beam. The process is called polariton parametric amplification and results in very large and ultrafast optical amplification of the probe beam. The model, based on a Hamiltonian of interacting bosons, suggests that the amplification is related to the coherence between polaritons. We demonstrate that in clearly designed samples, this coherence can be preserved almost up to room temperature, so that intersting applications of this phenomenon can be conceived. At the same time we have been able to improve dramatically the efficiency of the parametric process, making the microcavity an unprecedented optical amplifier.

2002

Chargement

Polariton

Les polaritons sont des quasiparticules issues du couplage fort entre une onde lumineuse et une onde de polarisation électrique. Plusieurs cas de figure sont possibles :

L'onde de polarisation est

Exciton

vignette|Représentation schématique d'un exciton de Frenkel, dans un cristal (points noirs). Un exciton est, en physique, une quasi-particule que l'on peut voir comme une paire électron-trou liée par

Champ magnétique

En physique, dans le domaine de l'électromagnétisme, le champ magnétique est une grandeur ayant le caractère d'un champ vectoriel, c'est-à-dire caractérisée par la donnée d'une norme, d’une directio