A1 mode Lamb wave on thin LiTaO3 for high frequency acoustic devices

Abstract

The Lamb waves and horizontal shear waves' propagation in LiTaO₃ thin plate is investigated as a function of Euler angles. Both velocity and electromechanical coupling factor largely depend on the plate's thickness. Around (0°, 30°, 0°), LiTaO₃ thin plate has a high velocity and a suitable coupling factor for a high frequency filter. Authors fabricated A₁ mode Lamb wave resonators in (0°, 39°, 0°) LiTaO₃'s thin plate. Lamb waves' velocities and leaky Lamb wave' velocities were measured by network analyzer and ultrasonic microscopy. Measured velocities correspond to the ones calculated by FEM. Velocities higher than 20,000 m/s were obtained. It is then shown that A₁ mode Lamb wave close to (0°, 30°, 0°) LiTaO₃ thin plate is suitable for high frequency devices.