Polarization-Encrypted Orbital Angular Momentum Multiplexed Metasurface Holography

TL;DR

This paper introduces a novel holographic encryption method using birefringent metasurfaces that multiplexes orbital angular momentum and polarization channels, enhancing security and enabling advanced applications like beam shaping and optical camouflage.

Contribution

It demonstrates the first use of OAM multiplexing with polarization for secure holographic encryption via metasurfaces, introducing a super-resolution-like technique for information retrieval.

Findings

OAM and polarization multiplexing enhances security.

Holographic images are reconstructed only with correct OAM and polarization.

The method enables applications in beam shaping and optical camouflage.

Abstract

Metasurface holography has the advantage of realizing complex wavefront modulation by thin layers together with the progressive technique of computer-generated holographic imaging. Despite the well-known light parameters, like amplitude, phase, polarization and frequency, the orbital angular momentum (OAM) of a beam can be regarded as another degree of freedom. Here, we propose and demonstrate orbital angular momentum multiplexing at different polarization channels using a birefringent metasurface for holographic encryption. The OAM selective holographic information can only be reconstructed with the exact topological charge and a specific polarization state. By using an incident beam with different topological charges as erasers, we mimic a super-resolution case for the reconstructed image, in analogy to the well-known STED technique in microscopy. The combination of multiple polarization channels together with the orbital angular momentum selectivity provides a higher security level for holographic encryption. Such a technique can be applied for beam shaping, optical camouflage, data storage, and dynamic displays.