Switching on and off acoustic waves through metamaterials has potential in noise canceling, underwater detection, and communication. However, traditional acoustic designs are challenging in manipulating underwater acoustic waves when the device thickness is less than wavelength. Here we report an alternative design of an underwater metasurface-based acoustic switcher to achieve this goal. The switching mechanism is revealed by combing acoustic diffraction of grating with mode conversion of double-layer PMMA plates. The device is tuned to control wave transmission by changing grating angle. Furthermore, we experimentally fabricate the metasurface acoustic switcher. The broadband-switching performance is realized to control underwater target detection and to produce binary digital encoding for acoustic waves. The proposed metasurface acoustic switcher offers the advantages of broadband performance and thin structure, which promises the opportunity for designing next-generation broadband-switching devices in underwater acoustic detection and communication.

• Received 7 November 2019
• Revised 14 January 2020
• Accepted 5 March 2020

DOI:https://doi.org/10.1103/PhysRevApplied.13.044019