Fig. 2. Characterization of the meta-atom with spin-multiplexed asymmetric reflections.

a An illustration of the topology and structure parameters. b, c A comparison of FDTD-simulated and theoretically calculated |r₊₊| and |r−−| of the meta-atom under normally incident spin-up and spin-down plane waves. The inset in Fig. 2b shows the current distributions (J_x) of both SRR₁ and composite SRR, illuminated by a plane CP wave. Here, theoretical calculations are based on the interference principle that is discussed above. FDTD-simulated reflective c amplitude and d phase spectra of the SRR₁ and SRR₂ meta-atom. e Absorption spectra that are calculated via $a_L=1-r_{LL}^2-r_{RL}^2$ for various values of δ. The geometrical parameters are R₁ = 2.2, R₂ = 1.4, w = 0.6, p_x = p_y = 7 (unit: mm), and ψ = 45°, and the gap widths of the inner and outer rings are 1.5 and 2 mm, respectively