Waveguide Modes with Threshold Nonlinearity

A three-layer structure is considered consisting of a nonlinear optical medium with an abrupt change in the dielectric constant, inside which there is a dielectric layer of finite thickness. It is shown that surface waves of two types of symmetry with a special field structure can propagate along the layers. It has been established that in the border regions in a nonlinear medium, regions of finite width with differing optical properties are formed. The formation of such boundary regions, as well as the existence of surface waves, occurs at interlayer thickness not exceeding a certain critical value.