Rayleigh-Wave Propagation on Bi12 GeO20

Theoretical values of mechanical displacement, potential, and velocity of surface waves propagating in the [001] direction on [110]-cut Bi12GeO20 are reported. The results of an experimental investigation performed at 50 MHz using interdigital transducers and optical probing are presented. The velocity measured is in excellent agreement with the theoretical value and the attenuation is very low, 0. 1 dB/μsec being an estimated upper limit. Second-harmonic generation which was measured by optical probing had an intensity proportional to the square of both the interaction length and the fundamental acoustic power, indicating nonlinear effects in the propagating medium at an acoustic input power of 28 dBm.