Nonlinear waves in a composite optical structure containing a dielectric layer between a photorefractive crystal and a medium with an exponential index profile

Abstract

Three-layered asymmetric structure with different optical properties of the layers is considered. The structure consist of a photorefractive crystal with diffusion nonlinearity and very weak dark intensity, which is separated by optically linear dielectric layer from medium with spatially distributed refractive index according with an exponential profile. The paper objective is a theoretical analysis of wave disturbances arising from the introduction of a dielectric waveguide layer between photorefractive and graded-index media. Waves of new four kinds are described theoretically by exact solutions to the wave equation with spatial inhomogeneous and intensity-dependent refractive index. The waves differ from each other in the distribution profile and the range of existence. Waves with both oscillating and non-oscillating field profiles inside the dielectric layer are obtained. It is found that the dielectric layer significantly affects the main characteristics of the field distribution in the waveguide structure in the direction transverse to the layers. It is shown controlling the values of the characteristics of the layers allows selecting the required field profile, which can be used to suppress oscillations or increase the field intensity in certain regions of a layered structure.