Bandwidth and Diffraction Efficiency Dependence on the Polarization of Light in Acousto-Optic Interactions

Abstract

We examine the case of an unguided, linearly polarized beam of light interacting with a surface acoustic wave. The focussed light beam enters a (LiNb03) crystal from the side and the diffraction efficiency is measured as a function of both deviation from Bragg angle and the sor p-polarization of the incident light. We give experimental evidence that for p-polarized light, the interaction bandwidth (i.e., the range of incident angles for which phase matching can be satisfied) for single diffraction can be twice as large as for the case of s-polarized light. This fact can be used advantageously in acousto-optic signal processing devices to increase dynamic range. We show results of an analysis which takes into account the particular interaction geometry and cornpare with experiment. We also indicate how to incorporate the gaussian nature of the incident optical beam.