Fig. 1. (a) Schematic diagram of the metadevice for different chiral responses at different operating frequencies when the LC optical axis is along the x, y, and z axes. (b) Optical microscopy image of the metasurface. (c) Placement of the bilayer metasurface and geometrical parameters of the meta-atom. (d) Schematic diagram of the metadevice configuration. (e) Schematic diagram of the THz-TDPS system.

Fig. 2. CD map as a function of THz frequency and LC rotational angle α when (a) θ=0°, (b) θ=90°, (c) θ=40°, and (d) θ=65°.

Fig. 3. Spatial mirror symmetry of the bilayer anisotropic metasurface with different θ: 0°, 90°, 0°–90°, when the LC is (a) absent and (b) present. The CD spectra under different configurations with different θ: (c) θ=0°, (d) θ=90°, (e) θ∈(0°,90°). (f) The CD spectra of the metadevice with respect to θ, when the LC optical axis is along the x, y, and z axes.

Fig. 4. For rotating the LC optical axis in the x–y plane: the experimental transmission spectra of (a) TLL, (b) TRL, (c) TRR, and (d) TLR with the bias voltage increasing from 0 to 100 V when illuminated by LCP and RCP waves.

Fig. 5. Tuning the LC optical axis in the x–y plane. (a) The experimental Co-CD spectra as the bias voltage increases from 0 to 100 V. (b) The simulated Co-CD spectra with the LC optical axis turned from 0° (x axis) to 90° (y axis). The frequency position and CD intensity of (c) Peak 1 and (d) Peak 2 at different bias voltages. (e) The polarization state of the output wave at 0.69 THz under LCP incidence and (f) that at 0.94 THz under RCP incidence as the bias voltage increases from 0 to 100 V.

Fig. 6. For rotating the LC optical axis in the x–z plane: the experimental transmission spectra of (a) TLL, (b) TRL, (c) TRR, and (d) TLR with the bias voltage increasing from 0 to 80 V when illuminated by LCP and RCP waves.

Fig. 7. Tuning the LC optical axis in the x–z plane. (a) The experimental Co-CD spectra as the bias voltage increases from 0 to 80 V. (b) The simulated Co-CD spectra with the LC optical axis turned from 0° (x axis) to 90° (z axis). The frequency position and CD intensity of (c) Peak 1 and (d) Peak 2 at different bias voltages. (e) The polarization state of the output wave at 0.6 THz under LCP incidence and (f) that at 0.92 THz under RCP incidence as the bias voltage increases from 0 to 80 V.

Fig. 8. Experimental and simulated (a) transmission and (b) phase difference of the monolayer anisotropic metasurface. (c) Experimental transmission spectra of the 300 μm thick LC layer. (d) The absorption coefficient of ordinary light and extraordinary light.

Fig. 9. For pure bilayer chiral metasurfaces without LC: (a) theoretical Co-CD spectrum when θ=0°, 40°, and 90°, (b) simulated CD spectra with respect to θ.

Fig. 10. Electric distribution of the metasurfaces under different conditions: (a) at 0.69 THz when LC optical axis is along the y axis, (b) at 0.92 THz when the LC optical axis is in the x–y plane and at an angle of 26° from the x axis, (c) at 0.945 THz when LC optical axis is along the x axis, (d) at 0.885 THz when the LC optical axis is in the x–z plane and at an angle of 40° from the x axis, and (e) at 0.725 THz when the LC optical axis is along the z axis.

Fig. 11. For rotating the LC optical axis in the x–y plane. The (a) PEA and (b) PRA of the output wave at 0.69 THz under LCP incidence, and the (c) PEA and (d) PRA of the output wave at 0.94 THz under RCP incidence as the bias voltage increases from 0 to 100 V.

Fig. 12. For rotating the LC optical axis in the x–z plane. The (a) PEA and (b) PRA of the output wave at 0.6 THz under LCP incidence, and the (c) PEA and (d) PRA of the output wave at 0.92 THz under RCP incidence as the bias voltage increases from 0 to 80 V.