Fig. 1. Operation principle of “leaf-type” hybrid metamaterial and it’s structural diagram. (a) Schematic diagram of half-wave plate (The polarization angle φ and incident angle θ are marked in the inset); (b) structural parameters of a unit cell in the proposed metamaterial

Fig. 2. Reflection polarization properties of “leaf-type” hybrid metamaterial when the VO₂ film is in different phase states. (a) and (b) Reflection coefficients of co- and cross-polarization; (c) and (d) Polarization Conversion Ratio (PCR)

Fig. 3. Polarization ellipses of reflected lights at the six specific frequencies under y-polarized illumination.

Fig. 4. Reflection coefficients and phases of the hybrid metamaterial for normal u and v polarization incidences when the VO₂ film is in different phase states. (a) and (b) Reflection coefficientsr_uu, r_vvand r_uv, r_vu; (c) and (d) reflection phases φ_uu, φ_vvand phase difference Δφ (normal u and v polarization incidences, as depicted by the inset)

Fig. 5. Instantaneous surface current distributions at critical frequencies. (a) 1.22 THz, (b) 1.68 THz, (c) 2.10 THz, (d) 2.61 THz for VO₂ film in the complete insulating state; (e) 1.22 THz, (f) 1.95 THz, (g) 2.10 THz, (h) 2.71 THz for VO₂ film in the complete metallic state

Fig. 6. Incident angle dependence of bandwidth-tunable half-wave plate components when VO₂ film is in the complete insulating and metallic states. (a) and (b) r_xy; (c) and (d) PCR

Fig. 7. Polarization angle dependence of bandwidth-tunable half-wave plate components when VO₂ film is in the complete insulating and metallic states. (a) and (b) r_xy; (c) and (d) PCR