Fig. 1. Schematic of the structure. (a) Top view and cross-section view of the unit cell; (b) schematic of the whole structure

Fig. 2. Reflection in the same polarization direction, cross-polarization direction and PCR for the u-polarization THz wave. (a) Before phase transition; (b) after phase transition; (c) PCR results for different conductivity of VO₂

Fig. 3. Surface current distribution. Before VO₂ phase transition, (a) f₁=1.61 THz, (b) f₂=1.88 THz, (c) f₃=2.07 THz; after VO₂ phase transition, (d) f₁=1.61 THz, (e) f₂=1.88 THz, (f) f₃=2.07 THz

Fig. 4. PCR of PI dielectric layer with different thickness. (a) Before phase transition; (b) after phase transition

Fig. 5. PCR changes with polarization angles. (a) Before phase transition; (b) after phase transition