Low-threshold continuous-wave Raman silicon laser

We report the first demonstration of a low-threshold continuous-wave (c.w.) Raman silicon laser based on a ring-resonator-cavity configuration. We achieved a lasing threshold of 20 mW, slope efficiency of 28% and an output power of 50 mW, with a 25 V reverse bias applied to the p-i-n silicon waveguides. This represents nearly a tenfold improvement in the lasing threshold and more than a fivefold improvement in both slope efficiency and output power over previous results. In addition, we demonstrate for the first time c.w. lasing with zero bias voltage. In this arrangement, the laser does not require an external electrical power supply, and we obtained a lasing threshold of 26 mW and laser output power exceeding 10 mW. The realization of low-threshold lasing and lasing with no external bias is a major advance towards producing practical silicon lasers based on stimulated Raman scattering, for applications ranging from telecommunications and interconnects to optical sensing and biomedical applications.