Effects of slant angle of metallic fish-scale structure on polarization conversion in the terahertz spectral range

Abstract

We report herein our investigation of planar terahertz (THz) metamaterials with metallic fish-scale structure. The fish-scale metamaterials with different slant angles were designed based on finite-difference time-domain simulations and fabricated on a dielectric substrate by using a laser-beam drawing system. Theoretical simulations indicate that the eigenpolarization states of the slant fish-scale metamaterials are corotating elliptical polarizations with orthogonal azimuth angles (i.e., the slant fish-scale metamaterials possess planar chirality in the THz spectral range). We measured the transmission spectra and polarization-conversion property of the fabricated metamaterials by using THz time-domain spectroscopy with a wire-grid polarizer. The results were consistent with the theoretical simulations. The experimental and calculation data clarify that both the azimuth angle and elliptical angle of the polarized THz wave transmitted through the planar metamaterial can be controlled by the slant angle of the fish-scale pattern. This study demonstrates the potential of the fish-scale metamaterials for polarization converters in the THz spectral range.