Optical gain and stimulated emission in silicon nanocrystals

Time-resolved luminescence measurements on silicon nanocrystal waveguides have revealed a fast recombination dynamics, related to population inversion which leads to net optical gain. The waveguide samples were obtained by thermal annealing of plasma enhanced chemical vapour deposited thin layers of silicon rich oxide Variable stripe length measurements performed on the fast emission signal have shown an exponential growth of the amplified spontaneous emission, with net gain values of about 10 cm(-1). Both the fast component intensity and its temporal width revealed threshold behaviour as a function of the incident pump. intensity. A modelling of the decay dynamics is suggested within an effective four level rate equation treatment including the delicate interplay among stimulated emission and Auger recombinations.