Ultra-Large-Coupling and Spurious-Free SH0 Plate Acoustic Wave Resonators Based on Thin LiNbO3.

This study lays a foundation for the design of the SH0 plate acoustic wave (PAW) resonators based on LiNbO3 plate, and are applicable to the ultra-wideband filters and next-generation tunable filters. The coupling coefficient ( k2 ) of SH0 mode is optimized to as high as 55% and wideband spurious are well controlled by analyzing the propagation characteristics of plate modes in LiNbO3. The SH0 mode is demonstrated to be slowly dispersive and features the superiority of interdigital transducer (IDT)-defining frequency over most other plate modes. On the device level, the transducer types and electrode materials are investigated and compared. In addition, for edge-reflected SH0 resonators, stopband dispersion analysis is provided and the longitudinal ripples are suppressed. For edge-reflected SH0 resonators, a novel perfect edge reflector is proposed with elimination of longitudinal spurious ripples.