Abstract
In this work, we demonstrate high performance shear-horizontal surface acoustic wave (SH-SAW) resonators and delay lines based on a thin film lithium niobate on insulator (LNOI) fabrication platform. To attain large effective electromechanical coupling left( {k_{{ ext{eff}}}^2} ight) and low bulk wave radiation, a SiO layer with subwavelength thickness is inserted between the lithium niobate thin film and the silicon substrate to form a simple and compact acoustic waveguide. The implemented LNOI resonators with wavelengths (λ) of 4, 6, and 8 μm achieve large k_{{ ext{eff}}}^2 of 28%, 25%, and 16% with corresponding maximum quality factor (Q) of 380, 560, and 980, respectively, featuring excellent figure of merit (FOM) up to 157. Moreover, the low loss acoustic delay line is also demonstrated to achieve a low insertion loss around 8.5 dB at 640MHz with a model-fitted wide fractional bandwidth around 4.5 % based on a conventional bidirectional transducer.