Investigation of Electromechanical Coupling and Quality Factor of X-Cut Lithium Niobate Laterally Vibrating Resonators Operating Around 400 MHz

In this paper we present laterally vibrating resonators (LVRs) based on X-cut lithium niobate (LN) exhibiting a maximum quality factor (Q) around 1200 and an electromechanical coupling (k
_t
²
) of 30%. This paper shows how the highest k
_t
²
ever attained in X-cut LN resonators can be combined with very high Q to achieve a resonator figure of merit (FoM = k
_t
²
· Q) of 360. In this paper, we validate the theoretical prediction of k
_t
²
versus the resonator orientation in the YZ plane and investigate what geometrical parameters mostly impact the Q of these devices.