Ellipticity Enhancement of a Terahertz Wave Circular Polarizer Made of 3D Chiral Metamaterial

Chiral metamaterials, such as helix arrays, have attracted significant attention due to their ability to manipulate the polarization properties of electromagnetic waves. The helix array can be used to fabricate a polarizer that selectively transmits circularly polarized light according to the handedness of the helix. However, the transmitted light is not purely circularly polarized due to unwanted circular polarization conversion. This letter presents numerical and experimental evidence that the random arrangement of helix orientation angle with respect to the polarization of incident light can reduce unwanted circular polarization conversion, making it possible to fabricate a circular polarizer with near-perfect ellipticity. The proposed method is applicable for efficient circular polarizer fabrication across the microwave, terahertz, and infrared regions of the electromagnetic spectrum.