Reconfigurable Janus metasurface with chiral meta-atoms for multi-channel vortex beams and holography multiplexing.

Multi-channel multiplexing metasurfaces have attracted considerable interest with the growing demand for multifunctional integration and enhanced communication capabilities. Dynamic tuning of electromagnetic waves with multiple degrees of freedom is a key approach to improving information processing capabilities. Metasurfaces with chiral meta-atoms and Janus metasurfaces with asymmetric transmission properties introduce new degrees of freedom for multiplexing technologies. It is a challenge to combine these two methods to achieve more degrees of freedom of multi-channel multiplexed metasurface. In this study, we present reconfigurable Janus metasurfaces with chiral meta-atoms based on vanadium dioxide (VO). Our results demonstrate that chiral meta-atoms enable dynamic switching between asymmetric transmission and reflection at varying temperatures. In the design of multi-channel vortex beams, this reconfigurable Janus metasurface can generate vortex beams with different spins by active control of propagation direction or temperature. In multi-channel metasurface holography designs, this chiral unit-based reconfigurable Janus metasurface can actively produce eight-channel metasurface holograms by manipulating chiral characteristics, propagation direction, or temperature. Additionally, in the design of metasurfaces for information encryption, four distinct metasurface holograms have been generated, which can be synthesized into a unique decrypted image. This research not only offers a novel approach for the design of multi-path multiplexing metasurfaces but also paves the way for applications in multi-channel structured light and promoting high-capacity and high-secure holographic applications. Consequently, it provides new possibilities for terahertz optical information encryption, data storage, and intelligent information processing.