Meta-holograms based on evanescent waves for encryption

Abstract

Benefiting from low absorption, large viewing angle, easy fabrication and low cost, metasurfaces are widely used in holograms. Theoretical calculation indicates that the evanescent wave can carry object information with higher spatial frequency, but this capability is usually ignored in existing research. We demonstrate a composite structure, which consists of a grating, multilayer structure and metasurface, to gather the information coded in the evanescent wave region under evanescent wave illumination and successfully reconstructed the original image of 2D and 3D holograms. This scheme shows large capabilities in hologram encryption, dynamic vision, and information storage.