Diffraction of light beams in media with longitudinal-transverse inhomogeneity

A theory has been developed to describe the propagation of planar wave beams in media with linear or nonlinear susceptibility modulated in the transverse and longitudinal directions. The diffraction in curved coupled waveguides and from wedge-shaped inhomogeneities is considered. Ray trajectories are found and the Schrödinger equation for the beam envelope is solved numerically. The spatial dynamics of energy redistribution in the beam cross section is described. Conditions for suppressing the beam spread due to the refractive index modulation are found.