Optical gain in monodispersed silicon nanocrystals

Stimulated emission from silicon-nanocrystal planar waveguides grown via phase separation and thermal crystallization of SiO∕SiO2 superlattices is presented. Under high power pulsed excitation, positive optical gain can be observed once a good optical confinement in the waveguide is achieved and the silicon nanocrystals have proper size. A critical tradeoff between Auger nonradiative recombination processes and stimulated emission is observed. The measured large gain values are explained by the small size dispersion in these silicon nanocrystals.