Metasurface-Assisted Optical Encryption Carrying Camouflaged Information

The superior capability of light manipulation makes optical metasurfaces capable of high-quality multichannel displays, demonstrating great potential in high-security optical encryption. Different from the previous multichannel nanoprinting metasurfaces based on the sophisticated nanostructure design, Malus metasurface can obtain multichannel meta-images only by arranging the orientations of single-sized nanostructures and thus have gained great attention. Here, an optical encryption scheme based on single-sized nanostructures is proposed by introducing camouflage strategy into Malus metasurfaces design processes to store multiple meta-images in different encryption levels. Experimental results demonstrate that the preset camouflage meta-image can be decoded by inserting a filter and a polarizer in the incident light path, while the decryption of real meta-image requires not only the insertion of a filter and polarizer in the incident optical path, but also the insertion of an analyzer in the outgoing optical path and setting them to the specific polarization direction. This work eliminates the consistency of encryption level in conventional multi-channel Malus metasurface, builds the differences of preset camouflage information and real information in decryption difficulty, and easily merges with other works, thereby paving a new way toward a high-security optical encryption technology.