Bianisotropic acoustic metasurfaces for wavefront manipulation

Abstract

Materials with sub-wavelength asymmetry and long-range order have recently been shown to respond to acoustic waves in a manner that is analogous to electromagnetic biansiotropy [Sieck et al. Phys. Rev. B 96, 104303, (2017)]. A characteristic of these materials is the generation of dipolar scattering when subjected to a uniform time-varying pressure field. This behavior leads to a characteristic acoustic plane-wave impedance that has a preferential direction, known as a polarization, which results in direction-dependent magnitude and phase of an acoustic field scattered from bianisotropic acoustic media. These materials can therefore be used as acoustic metasurfaces to control the reflected or transmitted acoustic fields. This work presents the use of bianisotropic acoustic media for wavefront manipulation through analytical and finite element modeling and discusses potential acoustic analogues to existing bianisotropic electromagnetic metasurfaces. [This work was supported by ONR and the National Science Foundation.]