Confocal microscopy and spectroscopy of nanocrystals on a high-Qmicrosphere resonator

We report on experiments where we used a home-made confocal microscope to excite single nanocrystals on a high- Q microsphere resonator. In that way spectra of an individual quantum emitter could be recorded. The Q factor of the microspheres coated with nanocrystals was still up to 10 9 . We also demonstrate the use of a prism coupler as a well-defined output port to collect the fluorescence of an ensemble of nanocrystals coupled to whispering-gallery modes.