Surface acoustic wave scattering by substrate edges

The harmonic surface acoustic wave (SAW) scattering at 90-degree corners of piezoelectric substrates is studied by FEM. The SAW is incident perpendicular to the vertical border. The dependences of the reflection and transmission coefficients on the radius of the fillet at the corner are found for 128°YX and YZ LiNbO₃ as well as ST-X quartz substrates. It is demonstrated that if the substrate is anisotropic, then a SAW can be scattered off differently at the right-hand border and the left-hand border. Computations for YZ LiNbO₃ illustrate possible levels of the anisotropy of the scattering for mutually reverse directions of incidence. However, if the substrate is oriented in a specific manner, then the scattering from the right-hand border is identical to the scattering from the left-hand border. There are four types of such orientations.