High-frequency asymptotics for Maxwell's equations in anisotropic media - Part II: Nonlinear propagation and frequency conversion

This paper is devoted to the derivation of the equations that govern the pr opagation and frequency conversion of pulses in noncentrosymmetric crystals . The method is based upon high-frequency expansions techniques for hyperbo lic quasi-linear and semilinear equations. In the so-called geometric regim e we recover the standard results on the frequency conversion of pulses in nonlinear crystals. In the diffractive regime we show that the anisotropy o f the diffraction operator involves remarkable phenomena. In particular the phase matching angle of a divergent pulse depends on the distance between the waist and the crystal plate. Finally we detect a configuration where th e beam propagation in a biaxial crystal involves the generation of spatial solitons thanks to an anomalous one-dimensional diffraction. (C) 2001 Ameri can Institute of Physics.