Single-sized multifunctional metasurfaces for simultaneous nanoprinting and holography inspired by tri-redundancy.

Multifunctional metasurfaces, where multiple functions can be integrated into a piece of metasurface, are preferably desired for compact systems with higher integration and subwavelength footprint. Particularly, metasurfaces for simultaneous nanoprinting and holography are one of the promising directions of development image display and information hiding in meta-devices. Here, inspired by tri-redundancy, a new, to the best of our knowledge, approach is proposed for generating a nanoprinting image in the near field and holographic image in the far field simultaneously, which can solve the extremum-mapping problem existing in single-sized scheme without increasing the complexity of the nanostructures. The tri-redundancy of image recognition, hologram designing and intensity modulation introduce an extra degree of freedom, which helps to find a balance between the two types of meta-images generated by utilizing the simulated annealing algorithm. A multifunctional metasurface composed of single-sized silver nanobricks with in-plane orientation has been fabricated to demonstrate the feasibility of encoding a binary image in the near field while reconstructing a 16-steps holographic image without twin-image in the far field. This multifunctional metasurface has flexible working modes, broadband working window and large robustness for fabrication errors, and it provides a simple design scheme for multifunctional integration. We expect it can empower advanced research and applications in high-end optical anticounterfeiting, image hiding and so on.