Nonlinear emission due to electron-polariton scattering in a semiconductor microcavity

Electron-polariton scattering is studied by photoluminescence spectroscopy in a GaAs/AlGaAs microcavity with an embedded quantum well containing a variable density electron gas. The photoluminescence spectra are measured as a function of two parameters: (a) The detuning energy between the cavity-confined photon and the heavy exciton and (b) the intensity of the laser that generates the electron gas. The integrated photoluminescence intensity varies nonlinearly with increasing electron density, showing a large enhancement that reaches a factor of 35 over the intensity observed without an electron gas. The spectra are analyzed in the strong coupling regime, by calculating the energy and electron gas density dependence of the electron-polariton scattering rates. The most effective scattering process is the dissociation of the charged exciton component in the polariton states.