Microcavities combining a semiconductor with a fused-silica microsphere

We report studies of a novel microcavity system that combines a semiconductor quantum well with a fused-silica microsphere. We show that excitonic photoluminescence from the quantum well couples efficiently into whispering-gallery modes. Using a resonant light-scattering technique, we demonstrate that the Q factor of the combined system exceeds 105. Our studies also point to the necessity of using semiconductor nanostructures with a capping layer no more than a few nanometers thick.