Theory for shear horizontal surface acoustic waves in finite synchronous resonators
An analytic approach is developed for simulating synchronous resonators employing shear horizontally polarized surface acoustic waves, such as surface transverse waves, and leaky surface acoustic waves on LiTaO/sub 3/ and LiNbO/sub 3/ substrates. The approach, based on a simplified parametrized Green's function theory, allows the description of the localization of the wave and the interaction with bulk acoustic waves. An analytic expression is found for the harmonic admittance of an infinite periodic electrode array, and approximate corrections for finite structures are presented. The model enables fast computation of the admittance of synchronous resonators, and it compares favorably with experiments and numerical simulations.
Acoustic loss mechanisms in leaky SAW resonators on lithium tantalate
We discuss acoustic losses in synchronous leaky surface-acoustic wave resonators on rotated Y-cut lithium tantalate substrates. Laser probe measurements and theoretical methods are employed to estimate the radiation of leaky waves into the busbars of the resonator and the excitation of bulk-acoustic waves. We find that the escaping waves lead to a significant increase in the conductance, typically in the vicinity of the resonance and in the stopband, but that they do not explain the experimentally observed deterioration of the electric response at the antiresonance. At frequencies above the stopband the generation of fast shear bulk-acoustic waves is the dominant loss mechanism.
Shallow Bulk Acoustic Wave Progress and Prospects
Shallow bulk acoustic wave propagation in piezoelectric crystals is reviewed from the standpoint of work reported to date. It is compared to bulk and surface acoustic waves as to properties and device potential. Singly and doubly rotated cuts are considered, as are piezoelectric transduction energy trapping, equivalent networks, as well as areas of future work such as new materials other than quartz, and nonlinear effects.