TM POLARIZED SURFACE WAVES PROPAGATING ALONG THE SURFACE OF A PHOTOREFRACTIVE CRYSTAL WITH NONLINEAR SELF-FOCUSING COATING

Abstract

Objective. A model of a composite waveguide structure based on a photorefractive crystal with a diffusion mechanism with a nonlinear self-focusing coating is considered. The Kerr effect is realized in the coating when the refractive index depends on the square of the amplitude of the fi eld strength (electric or magnetic). The other side of the coating is in contact with a medium that does not have any non-linear optical effects (dielectric or air).
Purpose. The aim of this work is to study the localization features of the fi eld along such a composite structure using, for example, the formation of a surface wave with TM polarization.
Methods and methodology. The system of Maxwell equations is used for describing the stationary distribution of the TM-polarized surface wave fi eld propagating along the interfaces of the layers. A special form of dependence of the refractive indices of the layers of the composite waveguide is chosen.
Results. A system of nonlinear equations is formulated for a component of the magnetic fi eld strength of a TM-polarized surface wave. The two types of solution of such system are found.
The solutions satisfy the conditions at the interfaces between the layers and the disappearance of the fi eld at infi nity in the truncated layers direction. Solutions of two types exist in different ranges of propagation constant values. They describe the surface waves with different localization profi les across the layers. The fi rst type of waves attenuates without oscillation and the second one attenuates with oscillations. It is shown that by adjusting the temperature of a photorefractive crystal, one can control the depth of localization of the fi eld in it and the period of spatial oscillations. The possibility of increasing or suppressing the field at the boundary of a photorefractive crystal has been established.
Conclusions. It is shown that the TM-polarized waves can propagate along considered waveguide structure surface. The properties of such waves are determined in dependence of optical characteristics of the waveguide.

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