Diffraction of Bleustein-Gulyaev waves at a periodic structure of shallow grooves

A theoretical model is developed for the diffraction of Bleustein-Gulyaev waves (BGW) by the periodic structure of shallow grooves on the surface of a piezoelectric crystal. The grooves are treated as surface perturbations, allowing neglect of multiple reflections between the faces of the wedge and two grooves. The model is a combination of the boundary perturbation technique and the theory of two-mode coupling. Expressions are derived for the characteristics of the BGW, the distribution and characteristics of the mechanical and electrical sources induced by the BGW, and coupling of surface acoustic waves in the array region. The Poynting theorem is employed to quantify the power of the resulting BGW. Sample results are provided from applications of the model to determine the behavior of BGWs arising from PZT-4 and PZT-5H piezoelectric ceramics.