Enhancement of leaky surface acoustic wave harmonics excitation using bonded dissimilar-material structures

Abstract

Abstract The enhancement of high-order surface acoustic wave (SAW) harmonics by increasing the metallization ratio was theoretically and experimentally investigated in high-performance bonded dissimilar-material structures. The simulation using a finite element method for 36°Y-cut X-propagating LiTaO3 (36°YX-LT)/AT-cut 90°X-propagating quartz (AT90°X-quartz) and 27°YX-LiNbO3/AT90°X-quartz was performed by setting the metallization ratio of the interdigital transducer to a/p = 0.8 (a: electrode width, p: pitch), and the LT and LN thin-plate thicknesses to h/λ = 0.05 (λ: wavelength) and 0.1, respectively. The fractional bandwidths for 36°YX-LT/AT90°X-quartz and 27°YX-LN/AT90°X-quartz were obtained to be 1.6% and 4.0%, respectively, which were larger than those for single LT and LN. For a leaky SAW (LSAW) resonator with a/p = 0.8 fabricated on 36°YX-LT/AT0°X-quartz, the resonance properties and temperature coefficient of frequency of LSAW fundamental waves and harmonics were measured. The measured fractional bandwidth increased from 0.8% to 1.4% for single LT.