Brillouin scattering from induced phonons excited by the ZnO piezoelectric thin film with a coaxial resonator

Brillouin scattering method is a nondestructive and noncontact technique to measure local longitudinal and shear acoustic velocities in the GHz range. However, the measurements of weak scattering from thermal phonons result in the lower measurement accuracy and longer measurement time than those of other methods, such as ultrasonic pulse techniques. To overcome these problems, a technique with induced phonons was developed using a ZnO piezoelectric thin film and a coaxial resonator. Especially, this technique enables simple measurement system without electrodes making use of evanescent electric field to ZnO film. In this study, ZnO piezoelectric thin film was deposited on curved and rear surfaces.