High-performance brillouin spectroscopy of phonons induced by a piezoelectric thin film with a coaxial microwave resonator

To overcome the low accuracy of acoustic velocity measurements based on Brillouin scattering from thermal phonons, we attempted to utilize induced coherent phonons, which cause intense Brillouin scattering. A ZnO piezoelectric film was used to induce gigahertz-range coherent phonons in a silica glass block sample. An evanescent electromagnetic wave leaked from a coaxial resonator was applied into the film to excite phonons. The scattered light obtained using this simple system was much more intense than that obtained from thermal phonons. This technique will improve the accuracy and reduce the measurement time.