Directional beam multiplexing using cylindrical holographic acoustic metasurfaces integrated with surface wave reflectors.

Recent advancements in acoustic metasurfaces have significantly improved beamforming and steering capabilities, with beam multiplexing emerging as a key enabler of multidirectional sound projection. This paper proposes a cylindrical holographic acoustic metasurface integrated with surface wave reflectors (SWRs) to realize efficient acoustic beam multiplexing. By transitioning from conventional planar designs to a cylindrical geometry, the proposed metasurface supports the simultaneous generation of multiple highly directional beams at distinct combinations of elevation and azimuthal angles. The integration with SWRs enhances beam collimation and suppresses side lobes, thereby ensuring high directivity and acoustic field confinement. Both simulations and experimental validations confirmed that the metasurface could steer multiple beams generated by a single monopole source in specific directions in 3D space; this capability can help ensure reliable performance across various applications such as sonar, medical imaging, and acoustic communication. The proposed approach represents a versatile and scalable conformal platform for spatially multiplexed acoustic beam steering, marking a significant advancement in the development of multifunctional acoustic metasurfaces.