Classification of Bianisotropic Metasurfaces from Reflectance and Transmittance Measurements

Abstract

Using fundamental electromagnetic properties of metasurfaces, we build a platform to classify reciprocal bianisotropic metasurfaces from typical experimental measurements and determine isotropic, anisotropic, bi-isotropic (chiral), and bianisotropic (so-called omega) properties. We provide experimental guidelines to identify each class by measuring macroscopic scattering parameters, that is, reflection and transmission coefficients upon plane wave illumination with linear and/or circular polarization. We explicitly provide a recipe of which metasurface properties can and cannot be inferred by means of the chosen polarization, reflection, and transmission properties. We also clarify common confusions in the classification of anisotropic versus chiral metasurfaces based on circular dichroism measurements presented in the recent literature.

Intrinsic Superchirality in Planar Plasmonic Metasurfaces

“…This implies that the magnetoelectric polarizabilities α xx em and α yy em are different from zero. 44 These results confirm that the metasurface contains a chiral property.…”

“…We can appreciate the shape and hexagonal arrangement of the inclusions. The latter can maximize the hot-spot density of the metasurface, in comparison to a classical (top-down, left−right) arrangement 44,45 to understand the behavior of uniform reciprocal bianisotropic metasurfaces, we consider the case when our sample is illuminated normally by either a linearly polarized (LP) or a CPL plane wave from either the forward direction (top, −z direction) or backward direction (bottom, z direction). We first measured the cross-polarized (xy and yx) coefficients of transmitted intensity for both propagation directions (±z direction); the results we obtained are reported in Figure 2.…”

Multi-band terahertz anisotropic metamaterial absorber composed of graphene-based split square ring resonator array featuring two gaps and a connecting bar

“…Metamaterials fall into the category of anisotropic metamaterials if they possess at least one of the following features: anisotropic geometries, anisotropic material within the metamaterial structure, or applying an external magnetic field to the metamaterial. Metamaterials featuring anisotropic geometries do not coincide with their mirror image at some rotational angles 1 .…”

Terahertz graphene-based multi-functional anisotropic metamaterial and its equivalent circuit model

“…Chirality can arise from chiral metamaterials or chiral molecules as sub-structures when anisotropy is introduced through metamaterials with anisotropic geometries, anisotropic material in the metamaterial structure, or applying a magnetic field. Metamaterials with anisotropic geometries do not superimpose on their mirror image at some degrees of rotation and can thus produce LD and/or CD ani 1 , 2 .…”