Highly directional acoustic wave radiation based on asymmetrical two-dimensional phononic crystal resonant cavity

The radiation properties of an asymmetrical two-dimensional phononic crystal resonant cavity with a point source inside are investigated experimentally. The resonant cavity is formed by two separated phononic crystals of different thickness, both of which consist of the same square array of steel rods in water. We observe highly directional acoustic wave radiation when a point acoustic source is put inside the cavity. The radiation field has a half-power beam width less than 6°. This design may serve as a highly directional acoustic source in applications.