L-Band LiNbO3/SiO2/Sapphire Longitudinal Leaky Saw (LLSAW) Resonators with High Figure of Merit

This work presents a set of high performance longitudinal leaky surface acoustic wave (LLSAW) resonators based on lithium niobate LN/SiO
2
/Sapphire (LNOS) characterized by a larger phase velocity. The LLSAW resonators on the proposed LNOS platform results a remarkable 9-fold improvement the figure of merit compared to the identical devices on LN/SiO
2
/Silicon platform. As a result, the LLSAW resonators demonstrated both a high-quality factor (Q
max
> 1010) and a large electromechanical coupling coefficient $\left( {k_{{\text{eff}}}^2 > 14.3\% } \right)$ which yielding a figure-of-merit $\left( {{\text{FoM}} = k_{{\text{eff}}}^2 \cdot {Q_{\max }}} \right)$ exceeding 145 for the first time in L-band region. These findings showcase a highly competitive performance compared to state-of-art thin film LLSAW resonators.