Polarization-sensitive nonlinear optical diffraction

Abstract When a laser beam is incident on a nonlinear grating with a laterally modulated second-order nonlinear coefficient, nonlinear diffraction of the noncollinear second-harmonic generation (SHG) signal occurs, with Raman–Nath nonlinear diffraction (NRND) being a prominent example. As these SHG NRND processes involve coupling between the fundamental-wave pump laser vectorial field and the SHG laser vectorial field through the second-order nonlinearity second-rank tensor of the nonlinear crystal, the nonlinear interaction between light and the nonlinear grating can be manipulated by adjusting the polarization state of the pump laser. In this paper, we derive the relationship between the polarization state of the incident light and the generated nonlinear diffraction signal based on the nonlinear coupled wave equation and experimentally validate the predicted diffraction characteristics. The results show that the optical properties of each order of NRND are highly sensitive to the polarization angle of the incident pump laser beam.