Whispering-gallery-mode lasing from a semiconductor nanocrystal/microsphere resonator composite

Spherical whispering-gallery-mode lasers employing CdSe/ZnS semiconductor nanocrystals (sec Figure, inset scale bar: 15 mu m) are assembled on a substrate using a simple, robust spin-coating fabrication method. The flexibility to choose the size of the microsphere template and the emission wavelength allows for the observation of single-mode lasing. At higher excitation intensities, lasing from higher multiexcitonic states is also observed.