Multifunction switching by a flat structurally tunable acoustic metasurface for transmitted waves

Reconfigurable curved metasurface for acoustic cloaking and illusion

“…This advantage establishes the foundation for dynamically manipulating acoustic waves at a broadband frequency range by using our helical metasurface. Multiple functions can be easily realized through the reconfiguration of only one metasurface, whereas the traditional metasurfaces with fixed configurations require costly and time/labor-consuming redesigning and fabrication [32][33][34][35]. Next, we first will exhibit two useful dynamic functions, including carpet cloak and ground illusion, by full-wave numerical simulations.…”

“…1(c). Based on the matched screw-and-nut mechanism [33][34][35], when the matched screw is tuned by rotating, the channel length characterized by the helical depth (h) will be changed. The scalar air-borne sound will propagate freely into the unit along the helical paths and is reflected from the upper surfaces of the matched screw.…”

“…Attempts to this end, little research has been done on the tunable acoustic metasurface [28][29][30][31][32][33][34][35].…”

“…For the space coiling metasurface, Zhao et al [33] designed a continuously tunable acoustic metasurface with individual unit components of a helix screwed inside a cylindrical thin plate for transmitted axial 3D focusing. The idea was then extended to 2D multifunction switching of a tunable metasurface [34]. The realistic solution to achieve broadband tunability of a flat acoustic metasurface with reflected multifunction was demonstrated numerically and experimentally in this space coiling framework [35].…”

“…From the above discussions, the ways to overcome the restriction of fixed and rigid acoustic metasurfaces with single or narrow band are to design a lossy structure or multilayer metasurfaces [28][29][30], or an independently adjustable unit [31][32][33][34][35] to change the formed geometry. Here, in the present work, a successful concept of a tunable metasurface for carpet cloak is proposed based on a type of helical units using matched screw-and-nut physical mechanism.…”