Multifold Integration of Printed and Holographic Meta-Image Displays Enabled by Dual-Degeneracy.

By virtue of the unprecedented ability of manipulating the optical parameters, metasurfaces open up a new avenue for realizing ultra-compact image displays, e.g., nanoprinting on the surface and holographic displaying in the far-field. The multifold integration of these two functions into a single metasurface can undoubtedly expand the functionality and increase the information capacity. In this study, a minimalist tri-channel metasurface is proposed and experimentally demonstrated with multifold integration of printed and holographic displaying, which can generate two N-bit grayscale images and a four-step holographic image simultaneously. Benefiting from exploiting the degeneracy of energy allocation and the degeneracy of nanostructure orientations, the functionalities of nanoprinting and holography are combined without the need of a large amount of nanostructures with varied dimensions, which would facilitate both the metasurface design and fabrication. The proposed scheme provides a new idea in enhancing the functionality and capacity of metasurfaces without complicating their design, which has promising prospects for applications in ultra-compact image displays, high-density optical storage, optical anti-counterfeiting and many other related fields.