Optical parametric amplification in silicon nitride waveguides for coherent Raman imaging.

Abstract

We present tunable waveguide-based optical parametric amplification by four-wave mixing (FWM) in silicon nitride waveguides, with the potential to be set up as an all-integrated device, for narrowband coherent anti-Stokes Raman scattering (CARS) imaging. Signal and idler pulses are generated via FWM with only 3\u2009nJ pump pulse energy and stimulated by using only 4\u2009mW of a continuous-wave seed source, resulting in a 35\u2009dB enhancement of the idler spectral power density in comparison to spontaneous FWM. By using waveguides with different widths and tuning the wavelength of the signal wave seed, idler wavelengths covering the spectral region from 1.1\u2009µm up to 1.6\u2009µm can be generated. The versatility of the chip-based FWM light source is demonstrated by acquiring CARS images.