Gigahertz Acoustic Delay Lines in Lithium Niobate on Silicon Carbide With Propagation-Q of 11174

This work demonstrates gigahertz wideband acoustic delay lines (ADLs) with record-breaking propagation-Q using a thin-film X-cut lithium niobate on silicon carbide (LiNbO3-on-SiC) platform. Benefiting from the high bulk wave velocity and excellent mechanical $\text{f}\times \text{Q}$ of SiC, the shear horizontal surface acoustic wave (SH-SAW) excited by unidirectional transducers propagates in the top-surface of LiNbO3-on-SiC with low acoustic loss. The zero power flow angle (PFA) of −3° to +Y axis is obtained through simulation analysis and experiment validation, which leads to acoustic wave transmission perpendicular to the electrodes. Oriented at zero PFA, the fabricated ADLs show scalable center frequencies from 1.19 GHz to 2.11 GHz, 3-dB fractional bandwidth ranging from 2.7% to 11.5%, and a record-high propagation-Q of 11174. The performance has shown the great potential of the LiNbO3-on-SiC acoustic platform for various signal processing applications.