| This paper describes full-wave analysis of the SiO2 overlay with finite thickness/metal grating/rotated YX-LN substrate structure. The influence of thickness and surface topology of the SiO2 overlay, metal grating selection (copper or aluminum) upon excitation and propagation characteristics of acoustic guided modes are discussed in detail. It is shown that in the structure there propagate several types of acoustic guided modes. One type of mode concentrates the energy near the metal grating, and becomes the piezoelectric boundary acoustic waves with relatively large electromechanical coupling when SiO2 thickness becomes semi-infinite. Another mode concentrates its energy near the top surface of the SiO2 overlay and becomes the Rayleigh-type SAW on SiO2 when thickness is semi-infinite. With an increase in SiO2 thickness, it rapidly loses its piezoelectric coupling. The remaining mode is a series of guided modes bounded in the SiO2 layer, in which the SiO2 layer behaves as a waveguide because of its low acoustic wave velocities. |