Ultra-Low Loss and High Phase Velocity Acoustic Delay Lines in Lithium Niobate on Silicon Carbide Platform

In this work, acoustic delay lines (ADLs) based on thin film lithium niobate (LiNbO
3
) on silicon carbide (SiC) substrate were firstly presented. Thanks to the high bulk wave velocity of SiC, the shear horizontal surface acoustic wave (SH -SAW) and longitudinal leaky surface acoustic wave (LL-SA W) can propagate with low loss simultaneously within the LiNbO3 thin film. The fabricated SH-SAW ADLs show a high phase velocity (vp) exceeding 5500 m/s, a minimum insertion loss (IL) of 3.6 dB, and an ultra-low propagation loss (PL) of 3.16 dB/mm. The fabricated LL-SA W ADLs feature an extremely high v
p
exceeding 9000 m/s, and a minimum IL of 8.7 dB. The demonstrated ADLs based on LiNbO
3
-on-SiC are promising for acoustic signal processing applications at GHz.