Analysis of leaky surface acoustic waves on LiTaO3 substrate

Leaky surface acoustic waves (LSAWs) propagating in arbitrary directions of rotated Y-cuts on LiTaO₃ substrates are investigated. The inherent physical behavior of LSAWs, consisting of coupled modes involving terms decaying into the substrate and a term representing a radiating bulk wave, is fully explained. To further reduce the insertion loss, all relevant effects influencing the device performance, e.g., diffraction spreading losses and spurious bulk waves, must be considered. The Y-rotated LiTaO₃ substrate with wave propagation in the crystalline X-direction is analyzed. Phase velocity and attenuation constant are computed for different rotation angles, as well as for different propagation directions, and the measured results are compared with those obtained from theoretical analysis