Modifying the polariton relaxation bottleneck by injecting an electron gas in a semiconductor microcavity

We report on the experimental study of polariton relaxation in the presence of a photo-injected electron gas. The occupation factor along the polariton branches is probed through angle resolved photoluminescence. The electron gas is shown to induce a redistribution of the population along the lower polariton branch with a strong population increase close to the center of the Brillouin zone. However, even in the presence of electrons, polariton-polariton scattering is shown to remain the most efficient relaxation process and the system is found to remain far from thermal equilibrium.