Surface wave delay line acoustooptic devices for signal processing

Abstract

Several acoustooptic devices have been developed for use as electronic signal processors at the Harry Diamond Laboratories. These devices use the Bragg interaction between a coherent light beam and surface acoustic waves propagating in a transparent crystalline delay line. Both real-time convolution and correlation of signals have been performed, and a real-time continuous Fourier transform has also been achieved. A programmable memory correlator has been demonstrated. This device uses a newly discovered photorefractive effect to store an image of a surface acoustic wave in a lithium niobate delay line. An acoustooptic implementation of the triple-product convolver is under active development. This device has been proposed for use in conjunction with charge-coupled-device chirp-Z-transform modules to perform very long discrete Fourier transforms and to do omega-k beam forming.