Spin-selected bifunctional metasurface for grayscale image and metalens.

With the extensive research on the Pancharatnam-Berry phase, metasurfaces have been widely designed as various cross-polarized nanodevices for circularly polarized (CP) illumination. However, co- and cross-polarized lights are rarely co-modulated by the metasurface. To fully utilize the transmitted light, we propose a spin-selected bifunctional metasurface composed of arrayed silver nanorods, integrating an amplitude-based grayscale imaging for co-polarized transmission and a phase-based metalens for cross-polarized transmission, under left-handed CP incidence. Moreover, such dual functionalities work well under right-handed CP incidence. Both experiments and simulations demonstrate the bifunctional performance as potential meta-devices.