Refraction and Reflection of Surface Acoustic Waves at Boundaries of Layered Anisotropic Substrates: Gold on Lithium Niobate

Acoustic surface-wave phenomena similar to optical refraction and reflection occur at boundaries of layered regions. In the case of piezoelectric substrates the anisotropy of the substrate must be considered in determining the reflection and refraction angles at such boundaries. The results of calculations of phase velocity and energy-flow direction as a function of propagation direction for the case of gold films on Y-cut lithium niobate are given. From these results the reflection and refraction angles at the boundaries of layers are determined. The theoretical results are compared with experimental observations of the deflection of surface-wave beams at gold film boundaries. These beam deflections were determined by optical imaging of the surface-wave beams using a laser diffraction technique.