Enhanced gain coefficient in Raman amplifier based on silicon nanocomposites

In this paper, silicon nanoparticles dispersed into a silica phase by sol-gel processing has been investigated by structural and nonlinear-optical characterization. The structural characterization has been performed by energy filtered and scanning transmission electron microscopy. A silicon nanoparticles mean radius of about 49 nm and a nanoparticle density of about 1.62 × 108 dots/cm2 have been obtained. Regarding nonlinear optics characterization, the observation of stimulated Raman scattering and the realization of a Raman amplifier based on silicon nanocomposites are described. Using a 1427 nm cw pump laser, amplification of Stokes signal, at 1542.2 nm, up to 1.4 dB/cm is demonstrated. A preliminary valuation of approximately a fivefold enhancement of the gain coefficient a significant reduction of threshold power are reported. Our findings have a potential interest for silicon-based Raman lasers.