Polarization-induced Fano resonances using wire-grid metasurfaces for the THz region

Metamaterials and, more recently, metasurfaces have been the focus of extensive research activities, as they play an ever-increasing role in the design of integrated photonics platform. Stacked metasurfaces are also currently investigated as an alternative route to design devices with enhanced optical properties or to propose exotic effects that cannot be achieved in single-layered metasurfaces. In this study, we theoretically show and experimentally demonstrate that stacked Metallic Wire-Grid Metasurfaces (MWGMs) can exhibit polarisation-induced Fano resonances owing to the basic polarisation properties of MWGM. We first present an original model based on an extended Jones formalism together with a circulating field approach, which reveals the underlying principle of polarisation-induced Fano resonances. Then, an experimental proof of concept was realised in the THz region to support the theoretical investigations using commercially available MWGMs, which shows good agreement with the model’s numerical results.