Thin-Film Lithium Niobate Acoustic Resonator with High Q of 237 and k2 of 5.1% at 50.74 GHz

Summary This work reports a 50.74 GHz lithium niobate (LiNbO
3
) acoustic resonator with a high quality factor (Q) of 237 and an electromechanical coupling (k
²
) of 5.17% resulting in a figure of merit (FoM, Q•k
²
) of 12.2. The LiNbO
3
resonator employs a novel bilayer periodically poled piezoelectric film (P3F) 128º Y-cut LiNbO
3
on amorphous silicon (a-Si) on sapphire stack to achieve low losses and high coupling at millimeter wave (mm-wave). The device also shows a Q of 159, k
²
of 65.06%, and FoM of 103.4 for the 16.99 GHz tone. This result shows promising prospects of P3F LiNbO
3
towards mm-wave front-end filters.