Experimental technique for the determination of surface acoustic wave grating impedance and velocity perturbations

Abstract

In this paper several new methods are presented whereby successive laser probe scans can be used to measure the reflection coefficient and velocity perturbation for a grating structure on a surface acoustic wave substrate. These techniques can be used to evaluate the perturbations presented by any overlay material arranged in a grating structure. This includes etched grooves, evaporated metals, and deposited dielectrics. The methods utilize the results presented previously [J. Appl. Phys. 60, 3532 (1986)] which indicate that the propagation of a beam profile can be very accurately predicted if a carefully measured slowness surface is used in conjunction with the angular spectrum of the plane-waves diffraction theory.