In- and out-going resonant Raman scattering from the cavity polaritons of semiconductor quantum microcavities

We present a resonant Raman scattering study of an on-resonance semiconductor quantum microcavity. Clear evidence for polariton mediation of the resonant Raman process in a microcavity is obtained. Two resonant peaks are observed in the out-going channel, arising from the upper and lower resonantly coupled exciton-photon (polariton) modes of the system. The resonant enhancement from the upper polariton state is much weaker than that of the lower state, due to the shorter dephasing time of the former. In the in-going channel, by contrast, only a single resonant peak is observed. We interpret this as arising from the much larger carrier density created by the photoexcitation, which for the in-going case is resonant in energy with the polariton states. The high carrier density leads to screening of the excitons, and decoupling of the excitonic and photonic states.