Optical measurement and numerical analysis of SAW propagation at dispersive delay line on Y-Z LiNbO3 substrate

Acoustic amplitude profiles of a dispersive delay line with a slanted chirp IDT on a Y-Z LiNbO₃ substrate are measured by an optical heterodyne interferometer. The results reveal that considerably strong waves arise from the boundary between the IDT and the bus bar, and become one of the causes of ripple in the frequency characteristics. Furthermore diffraction of the surface wave excited by the slated chirp IDT clearly shows considerable asymmetry between the front and rear directions. Simulations are performed on the basis of parabolic approximation theory and the results are compared with the optical measurements. When the anisotropy parameter calculated from the material constants of G. Kovacs et al. or J. Kushibiki et al. is used, the simulation results show good agreement with the experimental results.