Fast wave velocity measurement by Brillouin scattering using coherent induced phonon from ScAlN piezoelectric thin film

Brillouin scattering 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. To overcome this problem, a technique with artificially induced acoustic phonons was developed using a ScAlN film. We observed Brillouin scattering by induced longitudinal coherent phonons from ScAlN film deposited on the side surface of a silica bulk specimen. The intensity of induced acoustic phonons was experimentally studied.