Programmable Inverse-Designed Acoustic Coding Metasurfaces for Multifunctional Broadband Reflection

Abstract

In this paper, we report a kind of tunable reflection-type broadband acoustic coding metasurfaces (BACMs) based on a bottom-up topology optimization method. The BACMs is built by a row of identical coding units, which can be freely switched between the bits of “0” and “1” by controlling electromagnets. The coding units consist of the optimized irregular air channels and the connected air cavities. The bits “0” and “1” present a constant opposite phase difference in a wide frequency range due to the effect of the coupling resonances. Arbitrary coding sequences in BACMs can be rapid reconstructed by adjusting the electromagnets and then the acoustic focusing and acoustic splitter are demonstrated numerically and experimentally within the frequency range of [2.2, 4.4kHz].

Keywords: broadband, coding metasurface, programmable, inverse-designed