Collisional Broadening of Semiconductor Microcavity Polaritons

Abstract

We measure the effect of intensity on the homogeneous linewidth of two high finesse semiconductor microcavities in the strong coupling regime using degenerate four‐wave mixing. We find that the collisional broadening due to polariton–polariton scattering shows a threshold behaviour with intensity. At low intensities, a strong suppression is seen due to the small density of states available. Above threshold, the number of accessible states dramatically increases, giving a large increase in the collisional broadening. We also investigate the effect of modifying the dispersion curve, by detuning, on the threshold behaviour.