Low-power four-wave mixing in porous silicon microring resonators

We report the measurement of low-power continuous-wave four-wave mixing in porous silicon microring resonators operating in the 1550 nm telecom band. Resonantly enhanced stimulated four-wave mixing has been measured in rings with 25 mu m radius and quality factor around 5000 for pump powers as low as a few hundreds of microwatts. A waveguide nonlinear parameter gamma = 20 W-1 m(-1) has been determined. These results suggest further research on porous silicon for low-power nonlinear optics, possibly taking advantage of its tunable porosity.