Acoustooptic interactions in AlGaAs-GaAs planar multilayer waveguide structures

The acoustooptic interaction of guided optical waves and surface acoustic waves (SAW's) is studied in multilayered structures of dimensions of the order of those seen in multiple-quantum-well (MQW) structures. The guided mode profiles and SAW-induced electric field and strain profiles are used to calculate the diffraction efficiency, using an expression derived from coupled mode theory. Diffraction efficiency is plotted as a function of SAW frequency, and the effects of acoustic power, acoustic aperture, and material structure are considered. For a specific structure, the diffraction efficiency is seen to increase with increasing aluminum content for low concentrations and the opposite is seen for higher concentrations. This is explained in terms of the opposing effects of guided optical mode parameters and material properties. Possibilities for optimization of the diffraction efficiency through tailoring of the refractive index profile of the material structure are suggested.