Time-Resolved Emission from Semiconductor Microcavities

We present a time-resolved study of the light emission of a CdTe-based microcavity. In the nonlinear regime, under high excitation conditions, in the strong coupling regime, we observe pronounced beats of the intensity of the photoluminescence arising from the bottleneck region of the exciton-polariton band. These beats are very sensitive to the excitation density and vanish under weak pumping conditions. We attribute the beats to a new nonlinear coupling mechanism of optically active and dark crystal states, related to polariton-polariton scattering, which leads to mixing between bright and dark states.