IWERACTION OF HIGH-COUPLING LW SAW WITH BULK WAVES UNDER >lETAL.LIC-GRATING STRUCIUfE ON 36OYX-LiTaO j

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 negli- gibly 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 fast- shear waves. As to the velocity dispersion, the effect of the metallic-grating upon LSAW is quali- tatively similar to that on conventional SAW. Ex- perimental result using an open-circuited metallic- grating 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.