Plasmon-Mediated Whispering-Gallery-Mode Emission from Quantum-Dot-Coated Gold Nanosphere

Plasmons of gold nanostructures provide a powerful tool to enhance exciton-exciton coupling and energy transfer at spherical geometry, while quantum dots have confined excitons with strong optical oscillator strength and gain. Here, we report a plasmon-mediated whispering-gallery-mode emission from CdSe-ZnS quantum dot-coated gold nanosphere at room temperature. The whispering-gallery-mode emissions with different gold nanosphere sizes have been studied. Polarization-dependent emission is observed and explained. The decay dynamics of radiative emission is investigated by analyzing the photoluminescence decay spectrum. The underlying physical mechanism of the measured interference rings is further investigated by spatial distribution of photoluminescence intensity.