Flexible Polarization Manipulation Using Multi-band and Wide-angle Multi-function Reflective Polarization Metasurface for Terahertz Regime

In this paper, a metasurface-based reflective polarization converter for multi-band multi-functional polarization conversion with high-efficiency and wide-angle in the terahertz region is presented. The proposed metasurface cell is formed by a hybrid resonator composed of a modified double V and a stepped cut-wire, and a single-layer polyimide backed with gold. In the frequency band of 0.7–1.1 THz and 1.72–1.92THz, a linearly y-/x-polarized (LP) incident EM wave is converted into its cross-polarized direction with a polarization conversion ratio greater than 0.9 (PCR > 0.9). Also, in the frequency band of 1.05–1.71THz, an LP incident EM wave is converted into a circularly polarized reflective wave with an axial ratio (AR) less than 3 dB (AR < 3 dB). The multi-functional polarization conversion performance stays stable even though the incident angle up to \(40^\circ\). The numerical calculations, and physical insight analysis using surface currents distributions are studied. The results demonstrate that the proposed converter provides a new and efficient method to design high-efficient, incident angle insensitive, multi-band polarization converter for multiple polarization conversion in the terahertz frequency bands. The design can find potential applications in multi-band and multi-polarization THz communication, imaging, and sensing.