Fig. 1. Reconfigurable metasurface and its unit structure. (a) Three-dimensional diagram of metasurface; (b) three-dimensional diagram of unit; (c) top view of unit

Fig. 2. Reflection coefficient of incident terahertz wave and corresponding PCR. (a) Reflection coefficient of x-polarized wave and y-polarized wave at normal incidence; (b) PCR

Fig. 3. Current distribution of photosensitive silicon ring structure and metal layer when polarization wave is perpendicular incident. (a) f=2.30 THz; (b) f=2.90 THz

Fig. 4. Reflection coefficient and phase difference of terahertz wave at vertical incidence. (a) Reflection coefficient of x-polarized wave or y-polarized wave at vertical incidence; (b) phase difference of x-component and y-component of reflected wave

Fig. 5. Ellipticity and axial ratio of terahertz wave at vertical incidence. (a) Ellipticity of x-polarized or y-polarized terahertz wave at vertical incidence; (b) axial ratio

Fig. 6. Current distribution of photosensitive silicon ring structure and metal layer when polarization wave is perpendicular incident. (a) f=2.40 THz; (b) f=3.40 THz

Fig. 7. Absorption rate of terahertz wave in the designed device

Fig. 8. Equivalent circuit model and equivalent structural parameters of the proposed structure as an absorber. (a) Equivalent circuit model; (b) structural element equivalent parameter

Fig. 9. Surface electric field distribution under different frequencies. (a) f=2.90 THz; (b) f=4.50 THz

Fig. 10. Effect of incident angle on absorption performance. (a) Change of absorptivity with incident angle under TE wave incidence; (b) change of absorptivity with incident angle under TM wave incidence

Fig. 11. Reflection amplitude and phase of photosensitive silicon in 00 and 22 states when terahertz wave is incident vertically. (a) Amplitude; (b) phase

Fig. 12. Array layout and imaging effect. (a) Arrangement of photosensitive silicon in 00 and 22 states; (b) imaging effect when the frequency is 2.90 THz, terahertz wave is vertically incident, and the observation distance is 10 μm

Fig. 13. Reflection amplitude and phase of photosensitive silicon in 10 and 00 states when terahertz wave is incident vertically. (a) Amplitude; (b) phase

Fig. 14. Beam splitting effect at 3.3 THz of 1 bit coded metasurface arranged along the x direction with period of 0-0 and 0-1 when terahertz wave is incident vertically. (a) Three-dimensional far field scattering diagram; (b) normalized two-dimensional far field diagram; (c) two-dimensional electric field diagram

Fig. 15. Beam splitting effect at 3.3 THz of 1 bit coded metasurface arranged in chessboard pattern with period of 0-0 and 0-1 when terahertz wave is incident vertically. (a) Three-dimensional far field scattering diagram; (b) normalized two-dimensional far field diagram; (c) two-dimensional electric field diagram