Non-linear Optical Properties of Semiconductor Nanoparticle-Doped Glass Microspheres

Microspheres were fabricated by heating with a CO$_{2}$ laser ($\lambda $ = 10.6 $\mu $m) the sharp tip of a fiber pulled from CdTe-doped or Silicon-doped borosilicate glass. Nanoparticles were formed in the microspheres during the few seconds that it took for the microsphere to form under CO$_{2}$-laser irradiation. We have fabricated microspheres ranging in diameter from 10 $\mu $m to 300 $\mu $m. These microspheres contain nanoparticles ranging in diameter from 5 nm to 10 nm, as indicated by TEM. We have resonantly coupled light into the whispering gallery modes (WGM) of the microspheres using a tapered-fiber coupler. We have measured high optical quality factors (Q) of 2X10$^{4}$ for a 30 $\mu $m diameter CdTe nanoparticle-doped microsphere and 5X10$^{4}$ for a 300 $\mu $m diameter silicon nanoparticle-doped microsphere. We will present our results on a number of non-linear optical studies conducted on these microspheres and discuss the implications of these results towards making active optical devices.