Enhanced Raman scattering from sub-wavelength silicon gratings

A one-dimensional sub-wavelength silicon grating with enhanced Raman response is demonstrated. Furthermore, the polarization response of the Raman is investigated. This study shows that, contrary to intuitive expectation, the Raman intensity can be similar for both input polarizations: parallel and perpendicular to the ruling direction. This similarity is achieved due to inter-ridge coupling and polarization dependent characteristics of the grating. Through optimization of the ridge width and spacing, enhanced Raman intensity is realized in both polarizations, simultaneously. The results are further understood using a finite difference time domain model based on the light interaction with the grating for each polarization. (C) 2013 AIP Publishing LLC.