Enhanced spontaneous emission from semiconductor nanocrystals embedded in whispering gallery optical microcavities

Cavity-QED studies in a low-Q regime demonstrate enhanced spontaneous emission from CdSe/ZnS core/shell nanocrystals embedded in a polystyrene microsphere and provide important information on radiative dynamics in these quantum dots. The cavity-induced relative enhancement in photoluminescence decay rates depends sensitively on the relative contribution of radiative and nonradiative decay processes. The experimental results, including the temperature and nanocrystal size dependence of the time-resolved photoluminescence, suggest that the enhanced spontaneous emission arises from photoluminescence from the lowest dipole-allowed transition. For large nanocrystals, decay of the transition is primarily radiative in origin.