Fig. 1. Terahertz polarization converter based on skew-coupled symmetric cylinder structure. (a) 3D structure schematic; (b) 2D structure schematic

Fig. 2. Reflectance spectra at different gold pillar structures. (a) Single gold pillar; (b) three gold pillars; (c) five gold pillars

Fig. 3. Surface current distribution of the designed structure. (a) Upper pole plate; (b) lower pole plate

Fig. 4. Reflection spectra and polarization conversion rates of different polarized waves under different long axes of gold columns. (a)‒(c) Reflection spectra at R₂=8 µm, R₂=12 µm, and R₂=16 µm; (d)‒(f) polarization conversion rates at R₂=8 µm, R₂=12 µm, and R₂=16 µm

Fig. 5. Electric field distribution under different long axes of gold columns. (a) R₂ = 8 µm; (b) R₂ = 16 µm

Fig. 6. Circular polarization reflection spectra, scanning results distribution of R₂ parameters, and corresponding polarization conversion rate under different long axes of gold columns. (a) Circularly polarized reflection spectrum at R₂=16 µm; (b) distribution of scanning results for R₂ parameter; (c) circularly polarized reflection spectra at R₂=20 µm; (d) polarization conversion rate