Three-mode coupling in optically excited doubly periodic structures

This paper investigated the characteristics of a three-mode coupling in a dielectric slab waveguide with doubly periodic corrugation. Perturbation method was used to derive the coupled-mode equations and the reflection and transmission characteristics of the periodic waveguide of finite length were obtained. Results were obtained for the slab waveguide with doubly periodic corrugation when different laser densities were applied which affected the index of the undulation of the lower surface. The possibility of application of controllable rejection filter was discussed in the paper.