Top electrode shaping for harnessing high coupling in thickness shear mode resonators in Y-cut lithium niobate thin films

摘要

This paper reports a novel electrode shape for harnessing the high electromechanical coupling of the thickness shear mode (TSM) in Y-cut lithium niobate (LN) thin film resonators. To maximize the coupling, we follow Mindlin's [1-3] work, which uses two-dimensional equations of motion with transverse shear deformations to determine the most appropriate electrode shape for an anisotropic plate. We experimentally demonstrate an electromechanical coupling (k_t²) of ~37%, which agrees well with 3D COMSOL finite elemental method (FEM) simulations. Such high coupling resonators could find application in reconfigurable RF systems.