Theoretical investigations of nonlinear Raman-Nath diffraction in the frequency doubling process

We theoretically study the second-harmonic generation via nonlinear Raman-Nath diffraction in an optical medium with the spatial modulation of quadratic nonlinearity. We derive analytical equations that govern the emission properties of this nonlinear wave phenomenon. We also discuss how a substantial range of parameters such as the thickness of a nonlinear medium and the condition of a pump laser affect the strength of the emitted harmonic signals.