Surface waves at the boundary of a medium with a refractive index switching and a crystal with the diffusion-type photorefractive nonlinearity

A model is formulated, in which the patterns of the formation of nonlinear surface waves with a specific field structure are described. It is shown that there are two new types of waves of selected polarization that propagate along the contact of a photorefractive crystal with diffusion nonlinearity and a nonlinear optical medium with switching. Nonlinearity in such a medium is modeled by a stepwise change in the refractive index depending on the field amplitude. The field structure in the obtained surface waves consists of three components in different areas of the contacting media. As a result of the propagation of a localized light beam along the boundary in the border region, a zone of finite width is formed, characterized by a refractive index that differs from the rest of the medium. In the region behind such a domain, the field decreases exponentially with distance from the border region. The field can decrease with or without oscillations In a photorefractive crystal. The dependence of the propagation constant on the optical characteristics of the media and control parameters is obtained in an explicit analytical form.