Multifunctional acoustic metasurface based on an array of Helmholtz resonators

We demonstrate multifunctional acoustic metasurfaces that can simultaneously realize the same functionality or multiple different functionalities at multiple tunable frequencies. The fundamental physical mechanism is based on designing a supercell of Helmholtz resonators with multiple resonances operating at different frequencies. We theoretically, numerically, and experimentally demonstrate the achievement of multiple functionalities by the proposed designed metastructure, which produces extraordinary reflection at different angles and different acoustic focusing localizations under the same normal incidence. Our finding paves the way towards multifunctional compact acoustic devices and can lead to pragmatic contemporary applications such as multiple beam shaping, or functional devices with special dispersion properties.