Photoluminescence efficiency of semiconductor-microcavity-polaritons far from resonance

Temperature dependent photoluminescence experiments are performed in semiconductor microcavity structures exhibiting the strong coupling regime. Specific attention is focused on the case where the cavity mode is far below the quantum well exciton mode (i.e. when the detuning energy is larger than the Rabi splitting). The variations of the photoluminescence efficiency with detuning and temperature are not consistent with a phononassisted relaxation of the polaritons along their dispersion relations. The results can be better explained by a cavity-assisted observation of the wings of the broadened excitonic lines.