Tunable polarization-induced Fano resonances in stacked wire-grid metasurfaces

Abstract

Stacked metasurfaces are being investigated in light of exploring exotic optical effects that cannot be achieved with single-layered metasurfaces. In this article, we theoretically demonstrate that metallic wire-grid metasurfaces with specific polarization properties have the ability to induce tunable Fano resonances when they are stacked. The developed original model—combining a circulating field approach together with an extended Jones formalism—reveals the underlying principle that gives rise to the polarization-induced Fano resonances. The theoretical frame is validated in an experimental proof of concept using commercially available wire-grids and a terahertz time domain spectrometer. This unexplored possibility opens an alternative path to the realization and control of Fano resonances by using stacked metallic metasurfaces. Furthermore, these findings suggest that the polarization can be used as an additional degree of freedom for the design of optical resonators with enhanced and tunable properties.

All-dielectric one-dimensional gratings exhibiting Fano resonances in the terahertz region

“…They are well established in the literature [15][16][17][18][19][20][21][22], first described by Fano as a means to explain the asymmetric spectra from helium atoms subjected to inelastic scattering from electrons [23].…”

“…In the literature Fano resonances have been found for a multitude of different structures, or metamaterials (MMs) [21]. The complexity in the designs of the MMs ranges from one-dimensional gratings and structures such as split-ring resonators, to more intricate threedimensional structures [12,14,16,17,19,20,22]. Furthermore, the Fano resonances of the MMs have in different studies been shown to be highly tunable, hence enabling the possibility to tailor the MMs depending on the task [14,17,[19][20][21]25].…”

“…The complexity in the designs of the MMs ranges from one-dimensional gratings and structures such as split-ring resonators, to more intricate threedimensional structures [12,14,16,17,19,20,22]. Furthermore, the Fano resonances of the MMs have in different studies been shown to be highly tunable, hence enabling the possibility to tailor the MMs depending on the task [14,17,[19][20][21]25]. Sub-wavelength structures exploiting Fano resonances has been used for devices such as high-Q-factor optical filters [26,27] and single-material high-reflectivity mirrors [28].…”