Stimulated Scattering and Lasing of Intersubband Cavity Polaritons

We present a microscopic theory describing the stimulated scattering of intersubband polariton excitations in a microcavity-embedded two-dimensional electron gas. In particular, we consider the polariton scattering induced by the interaction with longitudinal optical phonons. Our theory demonstrates the possibility of final-state stimulation for the scattering of such composite excitations, accounting for the deviations from ideal bosonicity occurring at high excitation densities. By using GaAs parameters, we predict a quantum degenerate regime and lasing without electronic population inversion in an optical pumping configuration.