Analysis of resonant SAW - plate BAW interaction in periodical couplers

Surface acoustic waves (SAW) scattering into asemi-infinite solidhave been studied since the early 60-ies. In the case of a substrate with finite plate-like dimensions the scattering into bulk waves (BAW) is transformed into scattering to bulk plate modes. There have been some attempts to model the phenomenon but the most interesting case of interaction of SAW with BAW resonator, i.e. scattering in a quasi-perpendicular direction was not considered. The resonant interaction between Rayleigh SAW and near-onset Plate Waves in isotropic solids, through the coupling effect of an infinite periodical grating defined on the plate surface is theoretically described and its characteristics revealed. The analysis proposed is based on the Bloch theorem. The grating boundary conditions are considered assuming a weak surface perturbation. Further, the eigenmodes along with amplitude ratios inside such types of gratings are determined. Initial results on Gulyaev-Bljustein wave (GBW) - thickness shear mode (TSM) interaction are also presented.