Highly transparent twist polarizer metasurface

A twist polarizer metasurface for polarization rotation by an angle of 90° is proposed and realized at microwave frequencies. The metasurface consists of sub-wavelength metallic helices arranged periodically in a single layer and operates in transmission geometry with a nearly unity cross-polarization conversion coefficient at resonance. The structure exhibits low reflectivity R<0.06 within a decade-spanning frequency range of 0.1–5.5 GHz and is insensitive to the polarization orientation of the incident wave. Moreover, it can operate with high efficiency at oblique incidence angles of up to 35°. Such twist polarizer metasurfaces are potentially applicable as electromagnetic/optical isolators and frequency-selective polarization antennas.