Fig. 1. Scheme of the metasurface made of arrays of twisted nanorod dimers.

Fig. 2. Extinction cross sections of a dimer with twist angle π/4 and separation z0=200  nm for LCP and RCP light. Solid/dashed lines are the results calculated by CDM/FDTD.

Fig. 3. Transmittances of monolayer metasurfaces with θ=0,π/6,π/3,π/2 for LCP and RCP light.

Fig. 4. Transmittance of a bilayer metasurface with parameters z0=200  nm, Λx=600 nm, Λy=300  nm. (a), (c) θ=π/3 and ϕ=π/2; (b), (d) θ=π/6 and ϕ=5π/6. (a), (b) Results based on FDTD simulation; (c), (d) those based on the CDM.

Fig. 5. (a), (b) Transmittance of a metasurface with achiral building blocks [i.e., unit cell with nanorod dimer of twist angle π/2 (θ=π/4 and ϕ=3π/4)] based on FDTD simulation. (a) Λx=600  nm,Λy=350  nm,z0=150  nm (the condition of chirality-selective transparency is satisfied); (b) Λx=400  nm,Λy=350  nm,z0=150  nm (the condition of chirality-selective transparency is violated). (c)–(f) The electric field distribution (|E|) for nanorods A and B at wavelength of 600 nm. (c), (d) The distribution at the x–y cross-section plane with z=0 (rod A)/150 nm (rod B) for LCP light; (e), (f) the distribution at the x–y cross-section plane with z=0/150  nm for RCP light. The other parameters are the same as those in (a). (g) The g-factor corresponding to (a). (h) The transmittance versus the long-axis radius of the nanorods at a wavelength of 600 nm.

Fig. 6. Transmittance of LCP/RCP light associated with higher-order resonance based on FDTD simulation. (a) θ=π/4, ϕ=3π/4, Λx=1200  nm and Λy=300  nm, z0=150  nm. k=|L(±2,0)|. (b) θ=π/4, ϕ=3π/4, Λx=931  nm and Λy=781  nm, z0=150  nm. k=|L(±1,±1)|.

Fig. 7. Transmittance of LCP/RCP light with Λx=600  nm and Λy=350  nm calculated by the FDTD method. (a) z0=90  nm, θ=7π/20, and ϕ=13π/20. (b) z0=75  nm, θ=3π/8, and ϕ=5π/8.