Abstract: Tunable laser devices and methods of manufacturing such devices are disclosed. air-holes with defects that form an optical waveguide. The waveguide has a cross-sectional area whose dimensions are in sub-wavelength ranges, wherein the cross-sectional area is perpendicular to the propagation direction of light in the waveguide. The waveguide receives pump light and outputs Stokes light through Raman scattering. The laser device may include a photonic crystal made from silicon having air-holes with defects forming a pair of optically coupled cavities. The geometries of the cavities can be substantially identical to each other. The cavities are defined to cause a frequency-splitting difference between a frequency of pump light and a frequency of Stokes light to correspond to an optical phonon frequency in silicon through Raman scattering.