The investigation of point defect modes of phononic crystal for high Q resonance

Point defect cavity was constructed in a two-dimensional phononic crystal plate. It was excited by a small piezo chip in the cavity and the vibration of each point defect modes were detected by an optical interferometer. Point defect modes on 2D PC plate in vacuum, air and loaded with water were investigated theoretically and experimentally to make clear of Q factors, which are affected by inner attenuation, band gap effects and medium. The way to get high Q resonance has been found. It helps to design a new kind of resonator or sensor.