Interaction of High-Coupling Leaky SAW with Bulk Waves Under Metallic-Grating Structure on 36° YX-LiTaO3

Abstract

The paper deals with leaky SAW (LSAW) propagating under metallic-grating structure on 36OYX-LiTa03, and its interaction with bulk waves. Theoretical analysis has shown that the attenuation of LSAW unusually changes with frequency about the stopband of the grating: the attenuation is negligibly small at frequencies lower than the stopband, whereas it rapidly increases when the frequencies are raised above the stopband, and takes a maximum value of about O.ldB per wavelength. This suggests that the attenuation is mainly attributed to the interaction of LSAW with highly piezoelectric fastshear waves. As to the velocity dispersion, the effect of the metallic-grating upon LSAW is qualitatively similar to that on conventional SAW. Experimental result using an open-circuited metallicgrating was in good agreement with the theoretical prediction. However, the agreement was rather poor for a short-circuited metallic-grating. This may be due to the fact that in the short-circuited grating, the effects of mass loading and electrical perturbation upon LSAW propagation cancel each other.