Multifunctional comb-like acoustic metasurface for transmissive wavefront manipulation

Abstract

Precise and highly efficient wavefront modulation is greatly appreciated in acoustic engineering. Here, a comb-like acoustic metasurface is developed to efficiently manipulate the transmitted wavefront. The comb-like unit consists of an array of rigid rectangular partitions supported by a base. By adjusting the height of these rectangular elements, the entire 2π transmission phase shift can be achieved. The controllability of the phase shifts is demonstrated through theoretical and numerical analysis. A particle swarm optimization algorithm is employed to determine the height of the rectangular elements to achieve accurate target phase shift while maintaining high transmission efficiency. As a case study, highly efficient acoustic focusing and waveform conversion are achieved by comb-like metasurfaces, and the effect of unit deficiency on focusing performance is discussed. Furthermore, the application of comb-like metasurfaces to generate a self-bending beam and Airy beam is verified, and the acoustic beam of self-repair performance and robustness are demonstrated. In addition, acoustic focusing is realized using two symmetric Airy beams generated from the comb-like metasurface. Experiments are conducted to verify the effectiveness of the designed metasurfaces. This work presents an effective and feasible design solution for flexible wavefront modulation.