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 (LiNbO3) 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 vp exceeding 9000 m/s, and a minimum IL of 8.7 dB. The demonstrated ADLs based on LiNbO3-on-SiC are promising for acoustic signal processing applications at GHz.