We report on time-resolved photoluminescence measurements on a II-VI $\mathrm{Cd}\mathrm{Te}∕\mathrm{Cd}\mathrm{Mn}\mathrm{Te}$ semiconductor microcavity in the strong-coupling regime. Under nonresonant excitation, we observe the buildup of a large population in the polariton states close to the Brillouin-zone center with occupation factors larger than 10. A spectacular spectral narrowing is measured, together with a strong acceleration of the polariton relaxation. A simple rate equation model describing the stimulated polariton-polariton scatterings toward the lowest-energy polariton states gives a good overall description of the measured dynamic.

• Received 17 December 2004

DOI:https://doi.org/10.1103/PhysRevB.71.155311