Light waves mixing in nonlinear anisotropic media

A recent method for the solution of problems at the boundary of nonlinear electromagnetic media is extended to the anisotropic case for the purpose of studying the mixing between two strong electromagnetic waves in crystals. The general solution for the wave at the beat frequency is first derived for an unbounded medium on the hypothesis of weak harmonic generation. The boundary conditions at the plane surface of a nonlinear dielectric are then considered and the polarization characteristics of the fundamental waves are examined with the aim of obtaining a more efficient mixing.