P3J-2 Laser-Interferometric Analysis of Rayleigh Wave Radiation from a LLSAW Resonator

Rayleigh wave side radiation from a synchronous 1.6 GHz longitudinal leaky SAW (LLSAW) resonator on YZ-LiNbO₃ substrate is studied in this paper. Acoustic wave fields measured from the LLSAW resonator using a scanning laser interferometer are presented. The radiation angles extracted from the interferometric measurements are compared to theoretical calculations in a wide frequency range. Furthermore, the relative strength of the escaping Rayleigh wave beams evaluated from the interferometric measurements as a function of frequency is compared to the calculated coupling strength. These measurements reveal interesting effects not observed earlier. While the number of beams, the angles of radiation and their dependence on frequency can be reasonably explained, there are other effects whose explanation remains uncertain.