Polariton Spin Dynamics in II-VI Microcavities

Abstract

The spin dynamics of cavity polaritons, in the non-linear regime, present a novel and striking behaviour of the degree of polarization of photoluminescence. It reaches its maximum value at a finite time after excitation with a light pulse, and is strongly influenced by the exciton-cavity detuning. In the case of negative detuning, the relaxation towards K ∼ 0 states is governed by the polariton final state stimulated scattering, the emission is counter-polarized with the excitation and the polarization reaches very large negative values. In the case of positive detuning, the emission arises from the bare cavity mode, indicating a transition to the weak coupling regime; nevertheless, a very large positive polarization is observed. In addition to the large degrees of polarization of the emission, an energy splitting is observed between the two circularly polarized components of the photoluminescence, which is directly related to the anomalous behaviour of the polarization.