Analysis of Polarization Conversion Effect of the Multiple Order Diffracted Waves from a Large Periodic Chiral Metasurface

A metamaterials is a periodic nanostructure made with conductor and dielectric medium, which belongs to an artificial material. The metamaterials are mainly used to manipulate the polarization state of the electromagnetic wave. For a metamaterial, the lattice constant is smaller than the operated wavelength, therefore, the non-zeroth order diffraction effect does not exhibit, only the zeroth diffracted light is observed. By contrast, the non-zeroth order diffraction effect will appear if the lattice constant is larger than the operated wavelength. The diffraction phenomena is resulted from the contribution of the scattering effect by each meta-atom. Large-periodic metasurface is a two-dimensional nanostructure with lattice constant being larger than the operated wavelength of the electromagnetic wave. The multiple order diffraction effect is induced from the ensemble scattering effect of the two-dimensional nanostructure. The non-zeroth order diffracted waves also have polarization effect. The polarization conversion effect of the planar chiral material is deduced that this effect is resulted from the circular anisotropy, including circular diachroism and optical activity, the previous research articles are also utilized this principle to explain the the polarization conversion effect of a large periodic chiral metasurface. Nevetheless, it is necessary to clarify that the large periodic chiral metasurface still has the same polarization conversion mechanism with planar chiral metamaterial. This research project infers that the polarization conversion effect of the large periodic chiral metasurface behaves like the scattering of the V-antenna array as a theoretical basis. The experimental verification will be performed by measuring the Mueller matrix of the zeroth diffraction order and non-zeroth orders diffraction transmission from the large periodic chiral metasurface via a Mueller matrix ellipsometer. In order to verify the theoretical assumption, the circular anisotropy, linear anisotropy, and depolarization of the large periodic chiral metasurface will be characterized by using the polar decomposition of the Mueller matrix ellipsometer.

Project ID:PB10608-2399
External Project ID:MOST106-2221-E182-045