Optimum cut direction of Lithium Niobate as substrate in surface acoustic wave devices

摘要

A cut direction, rotated ZY cut of Lithium Niobate (LN), is studied. LN is a good piezoelectric crystal and it can be used as substrate of surface acoustic wave devices. In this paper, surface acoustic wave equations, including basic equations and boundary condition equations, are deduced. According to these equations the surface acoustic wave velocities are systematically calculated using a circle iterative method for LN along different directions in optimum decoupling acoustic sagittal YZ plane. The electromechanical coupling coefficients for rotated ZY cut LN are also calculated. The optimum cut direction of the LN crystal piece as substrate of surface acoustic wave devices is determined by the largest electromechanical coupling coefficient.