Bonded planar structures for efficient surface-wave devices

Generation of surface acoustic waves in non-piezoelectric solids using edge bonded rotatedY-cut lithium niobate transducers

“…of a piezoelectric layer deposited onto the substrate surface, leads to difficulties for slow SAW velocity substrates, owing to the unusual fast-on-slow dispersion properties obtained (single mode behaviour, with propagation allowed for a piezoelectric layer thickness between zero and a fraction of acoustic wavelength) [6]. The acoustic transfer method [7] uses a sandwich structure (piezoelectric material/nonpiezoelectric substrate/piezoelectric material), with excitation via interdigital transducers engraved on the piezoelectric parts; such an assembly is difficult to bond with perfectly aligned surfaces and proves to be fragile. The mode conversion of a bulk acoustic wave (BAW) into a SAW on a surface grating [8] and the use of edge bonded piezoelectric platelet transducers [9,10] are other candidates, which appear to be the most attractive for SAW excitation on slow non-piezoelectric substrates.…”