Determination of LiTaO3 acoustic physical constants at hypersonic frequencies from bulk and surface wave velocities

Abstract

Using Brillouin scattering, we have measured the velocity angular dispersion of the surface and bulk acoustic waves in X-cut and 36° Y-cut LiTaO3. The complete set of twelve independent acoustic physical constants at hypersonic frequencies is evaluated using a simultaneous fit to only the velocity angular dispersion data on both surface Rayleigh and bulk acoustic waves. In comparison to physical constants determined in the ultrasonic frequency range, our acoustic constants yield better agreement between theory and experiment for the angular dispersion of the surface Rayleigh and second leaky wave velocities. Additionally, computation based on these acoustic constants has accurately predicted the velocity angular dispersion of the bulk waves and their scattering coefficients.