Surface Waves at the Boundary of a Medium with a Refractive Index Switching and a Crystal with the Diffusion-Type Photorefractive Nonlinearity

It is formulated a model, within which, regularities for formation of nonlinear surface waves with a specific field structure are described. It is shown that there are two new types of waves of chosen polarization, which propagate along the contact of a photorefractive crystal with diffusion nonlinearity and a nonlinear optical medium with switching. Nonlinearity in this medium is modelled by a stepwise changing the refractive index depending on the field amplitude. The field structure in the obtained surface waves consists of three components in different regions of contacting media. The propagation of a localized light beam along the boundary at the near-boundary region results in formation of an area of a finite width, which has a refractive index that is different from the remaining medium. The field exponentially decreases in the region behind this domain when moving away from the near-boundary region. In a photorefractive crystal, the field can decrease with oscillations or without oscillations. The dependence of the propagation constant on optical characteristics of media and guiding parameters is derived in the explicit analytical form.