Mid-Infrared Raman-Enhanced Four-Wave Mixing in Silicon Waveguides

Four-wave mixing (FWM) is an important nonlinear process for wavelength conversion and photon-pair generation. Owing to the high third-order nonlinearity and tight optical confinement, integrated silicon waveguides have emerged as convenient platforms for the observation of FWM processes using continuous-wave (CW) pump sources with optical powers typically employed in communication systems [1]. However, without resorting to pulsed pump sources or complex resonator geometries, the conversion efficiencies in these chip-based systems are typically very low [2]. An alternative solution to enhance the conversion in FWM interactions is coupling the parametric nonlinear process with the resonant Raman response of the material [3]. This is particularly useful when extending the operation into the mid-infrared (MIR) region where the pump powers can be low, and where there is interest for applications in free space communications, optical imaging, and sensing [4].