Fig. 1. Schematic diagram of the unit-cell of metasurface. (a) Top view; (b) Lateral view; (c) Schematic illustration of function

Fig. 2. Transmission ((a), (b)) amplitude and ((c), (d)) phase of the designed metasurface structure under the incident linearly polarized wave

Fig. 3. (a), (b), (d), (e) The induced surface current and (c), (f) electric field distributions of unit-cell structure at (a)-(c) f₁ = 0.701 THz and (d)-(f) f₂ = 1.663 THz for the incident LCP waves along the −z axis direction

Fig. 4. When the rotation angles of the two different resonator of the designed unit-cell structure are rotated with 8 different angles at an interval of 22.5º, the simulated (a), (c) amplitude and (b), (d) phase under the transmitted RCP wave at the (a), (b) lower and (c), (d) higher frequency range

Fig. 5. (a) Schematic diagram of unit-cell with DCSR structure and 8 different rotation angles and the amplitude and phase of the transmitted RCP wave at 0.701 THz; (b) The unit-cell with RMP structure and 8 different rotation angles and the amplitude and phase of the transmitted RCP wave at 1.663 THz

Fig. 6. Four kinds of metasurface for generating the vortex beam with topological charge numbers, (a) l = +1, (b) l = +2, (c) l = +3, (d) l = +4

Fig. 7. [in Chinese]

Fig. 8. Phase purity plots with topological chargel

Fig. 9. 2D array of the designed metalens. (a) Schematic diagram; (b) Phase distribution

Fig. 10. The electric field distributions in the (a) xoz plane; (c) xoy plane for the transmitted RCP wave at 1.663 THz; (b) The power distributions at the focal point along x axis for the transmitted RCP wave; (d) The power distributions along the axis of the metalens