Two waves interaction in layered photonic structure at big phase mismatching

Abstract

Self-focusing of optical Gaussian pulse with the axial-symmetric profile of the beam due to cascading SHG at the big phase mismatch in the layered photonic crystal is considered. We show the possibility of strong self-focusing of the optical radiation in such conditions: a maximum intensity increases 70 (and more) times in comparison with the intensity of incident optical beam. Gaussian profiles of beam and Gaussian shape of pulse are preserved with sufficient good accuracy in the section of first or second nonlinear focus realization. These characteristics of optical radiation remain the same after leaving the pulse of the photonic crystal. For corresponding choice of interaction parameters the losses of energy at fundamental wave because of its conversion to the wave with double frequency is less than 5%. An influence of the incident intensity of laser pulse and the crystal length on the process of self-focusing is investigated also.