Fig. 1. Diagram of the metasurface zone plate encryption

Fig. 2. Modulation mechanism of metasurface zone plates. (a) The top and side views of the meta-atom; transmission (b) and phase (c) of the meta-atom with different sizes along x-polarization under the x-linearly polarized light with the wavelength of 633 nm; transmission (d) and phase (e) of the meta-atom with different sizes along y-polarization under the y-linearly polarized light; under the left-circularly polarized incident light, the metasurface (a1) consists of the odd metasurface zone plate (a2) and even metasurface zone plate (a3), where the amplitude and phase of the former were exhibited in Figs. (a4) and (a5) and those of the latter were exhibited in Figs. (a6) and (a7)

Fig. 3. Encoding information of transmitted circularly polarized light. (a1)(a2) QR codes; (b1) QR codes generated amplitude-only hologram; (b2) QR codes generated phase-only hologram; (c1) calculated encrypted intensity profile in the far field of the amplitude-only hologram; (c2) calculated encrypted intensity distribution in the far field of the phase-only hologram

Fig. 4. Hologram phases on the odd annular zones of the transmitted right-handed (a1) and left-handed (b1) circularly polarized light under the left-handed circularly polarized light, and the corresponding output phase distributions along the x-direction (c1) and y-direction (d1) under the x- and y-linearly polarized lights, respectively. The corresponding geometric phase is shown in Fig. (e1). The hologram phase on the even zones of the transmitted right-handed (a2) and left-handed (b2) circularly polarized light under the left-handed circularly polarized light, and the corresponding output phase distributions along the x-direction (c2) and y-direction (d2) under the x-and y-linearly polarized lights, respectively. The corresponding geometric phase is shown in Fig. (e2)

Fig. 5. Simulated holographic images at the designed distance of z=14.1 mm for the transmitted hybrid circularly polarized light, right-handed circularly polarized light and left-handed circularly polarized light under the left-handed circularly polarized incident light, respectively