Split-Bridged Disk-Like Terahertz Metasurface: Enabling Ultra-Broadband Asymmetric Transmissive Co-to-Cross Polarization Conversion

This paper proposes an ultra-broadband transmissive polarization converter with an asymmetric transmission characteristic operating in the terahertz (THz) frequency range. The proposed design comprises a tri-layer metasurface structure, where a split-bridged disk-like resonator is sandwiched between two perpendicularly oriented grating layers separated by dielectric spacers. This configuration enables the efficient conversion of linearly polarized waves into their cross-polarized counterparts under normal incidence, achieving a high polarization conversion ratio exceeding 90% across the frequency range of 1.19-9.0 THz.