J. Koskela et al., Mechanism for acoustic leakage in surface-acoustic wave resonators on rotated Y-cut lithium tantalate substrate, APPL PHYS L, 75(17), 1999, pp. 2683-2685
We discuss an acoustic loss mechanism in surface-acoustic wave resonators o
n 36 degrees YX-cut lithium tantalate substrate. Recent acoustic field scan
s performed with an optical Michelson interferometer reveal a spatially asy
mmetric acoustic field atop the busbars of a resonator, giving rise to acou
stic beams which escape the resonator area and lead to undesired losses. He
re, we link the phenomenon with the inherent crystalline anisotropy of the
substrate: the shape of the slowness curves and the asymmetry of the polari
zation for leaky surface-acoustic waves, propagating at an angle with respe
ct to the crystal X-axis. (C) 1999 American Institute of Physics. [S0003-69
51(99)01843-4].