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G. Malpuech

Publications and source records attributed to G. Malpuech.

94 records · Page 6Linked to original sources

Nonlinear effects in spin relaxation of cavity polaritons

We present the general kinetic formalism for the description of spin and energy relaxation of the cavity polaritons in the framework of the Born-Markov approximation. All essential mechanisms of polaritons redistribution in reciprocal space together with final state bosonic stimulation are taken into account, from our point of view. The developed theory is applied to describe our experimental results on the polarization dynamics obtained in the polariton parametric amplifier geometry (pumping at so-called magic angle). We have experimentally confirmed that the anisotropy of the polariton-polariton interaction is responsible for the build up of the cross-linear polarisation of the signal. The long-living linear polarization is observed at zero detuning. Under elliptical pumping, we have directly measured in the time domain and modelled the effect of self-induced Larmor precession.

cond-mat.mes-hall↗

Optical Anisotropy and Pinning of the Linear Polarization of Light in Semiconductor Microcavities

We report a strong experimental evidence of the optical anisotropy in a CdTe-based microcavity: the polarization of light is pinned to one of the crystallographic axes independently on the polarization of the excitation. The polarization degree depends strongly on the excitation power, reaching almost 100 % in the stimulated regime. The relaxation time of the polarization is about 1 ns. We argue that all this is an effect of a splitting of the polariton doublet at k=0. We consider different sources for the splitting and conclude that the most likely one is optical birefringence in the mirrors and/or the cavity.

cond-mat.mtrl-sci↗

Statistics of excitons in quantum dots and the resulting microcavity emission spectra

A theoretical investigation is presented of the statistics of excitons in quantum dots (QDs) of different sizes. A formalism is developed to build the exciton creation operator in a dot from the single exciton wavefunction and it is shown how this operator evolves from purely fermionic, in case of a small QD, to purely bosonic, in case of large QDs. Nonlinear optical emission spectra of semiconductor microcavities containing single QDs are found to exhibit a peculiar multiplet structure which reduces to Mollow triplet and Rabi doublet in fermionic and bosonic limits, respectively.

cond-mat.mes-hall↗

Order parameter dynamics of a Bose-Einstein condensate of exciton-polaritons in semiconductor microcavities

It is shown theoretically that Bose condensation of spin-degenerated exciton-polaritons results in spontaneous buildup of the linear polarization in emission spectra of semiconductor microcavities. The linear polarization degree is a good order parameter for the polariton Bose condensation. If spin-degeneracy is lifted, an elliptically polarized light is emitted by the polariton condensate. The main axis of the ellipse rotates in time due to self-induced Larmor precession of the polariton condensate pseudospin. The polarization decay time is governed by the dephasing induced by the polariton-polariton interaction and strongly depends on the statistics of the condensed state.

cond-mat.mes-hall↗