Langasite Resonator with Non-uniform Electrode Thickness: Design, Simulation, and Fabrication

Thickness-shear langasite resonator with non-uniform elliptical electrodes was designed, simulated, and fabricated to investigate the effects of varying electrode thickness on the spurious mode vibrations. A 3D FEM study was conducted to determine the optimal electrode design and verify the electrode design theories reported in literature. Simulated results showed 11% higher peak displacement for the optimized stepped design compared to that of the standard key-hole pattern, which can be attributed to enhanced energy trapping. Test results of the fabricated resonators also demonstrated similar improvements. Higher quality factor, enhanced suppression of spurious vibrations, and wider separation between the resonant and spurious mode were observed for the resonator with stepped electrodes compared to circular electrodes. The results verify our optimized design and demonstrate great potential for langasite-based sensors.