Four-channel metasurface for multiplexing images under two nonorthogonal polarization states

By its unparalleled capacity to manipulate optical parameters, metasurfaces demonstrate the ability to simultaneously manipulate the amplitude and phase of incident light. Exhibiting both near-field nanoprinting images and far-field holography images is a quintessential illustration of this capability. In preceding investigations, image multiplexing commonly transpires within the single polarization state or orthogonal polarization states, thereby exhibiting a deficiency in terms of information security when contrasted with the nonorthogonal polarization states. In this research, a multifunctional metasurface with the capability of exhibiting four-channel images has been proposed by using a nanobrick as a quarter-wave plate. Through the adjustment of the orientation angles of each nanobrick, nanoprinting can be displayed under both linearly and circularly polarized light. Building on this, the propagation phase is combined with the geometric phase to generate diverse phase delays, enabling the metasurface to be multiplexed under two nonorthogonal polarization states to achieve four-channel image displays. Intriguingly, bidirectional nanoprinting and bidirectional holography can be achieved by altering the direction of incidence polarization states. The proposed metasurface platform can open new possibilities for creating compact multifunctional optical devices, while also enhancing applications in multichannel image displays, information anticounterfeiting, and encryption.