Fig. 1. Unit cell structure of polarization converter. (a) Three-dimensional view of unit cell; (b) top view; (c) side view

Fig. 2. Relationship among reflection coefficient, PCR, and frequency

Fig. 3. Electric field distributions of metasurface at different frequencies. (a) 1.055 THz; (b) 1.380 THz

Fig. 4. Current distribution on different surfaces at two resonant frequency points. At frequency point of 1.055 THz, (a) current distribution on surface of graphene, (b) current distribution on metal surface at bottom; (c) vector decomposition of induced magnetic field; at frequency point of 1.380 THz, (d) current distribution on surface of graphene, (e) current distribution on metal surface at bottom

Fig. 5. Two eigenmodes of polarization converter. (a) Electric field vector decomposition graph; (b) amplitude of eigenmodulus; (c) phase corresponding to amplitude of eigenmodule

Fig. 6. PCR spectra at different incident angles

Fig. 7. PCR spectra of metasurface under different graphene parameters. (a) When the relaxation time is fixed at 1.0 ps, PCR spectra under different Fermi level; (b) when the Fermi level is fixed at 0.4 eV, PCR spectra under different relaxation time

Fig. 8. Relationship between PCR and frequency under different conditions. (a) Thickness of medium layer; (b) period; (c) angle