A numerical study of beam propagation in multilayer planar waveguide with optically nonlinear medium

The extended coupled mode equation incoporating the intensity dependent refractive index (IDRI) nonlinear optical effect of the medium was applied to a basic study of beam propagation in a symmetrically configured five - layer planar structure composed of two optically coupled waveguides with identical optically nonlinear guiding media. The three cladding layers are constituted of linear optical materials of the same refractive index. The result of this study and the result of simulation employing an extended Finite-Difference Beam Propagation Method explicitly demonstrate the feasibility of developing an optical device serving both as an all optical directional coupler and optical switch using the basic multilayer planar structure considered in this study. Restricting ourselves to the lowest TE waveguide modes, the power transfer efficiency and coupling length L-c were determined and described as functions of the input light intensity and the waveguide parameters such as the waveguide separation and the refractive indices.