Broadband coherent anti-Stokes Raman scattering in silicon

In silicon devices, the spectral bandwidth of coherent anti-Stokes Raman scattering (CARS) is limited by the narrowband nature of the Raman process in this medium. In this Letter, we report the observation of broadband wavelength conversion in silicon through CARS enhanced by the self-phase-modulation-induced spectral broadening of the optical pump. The CARS conversion over a bandwidth substantially greater than the intrinsic Raman linewidth is demonstrated yielding conversion efficiencies as high as 1%. Numerical simulations are performed to explain the spectral features observed in the spectrum of the anti-Stokes signal.