Metasurface‐generated Spin‐multiplexed & Grafted Perfect Vector Vortex Beams for High‐dimensional Optical Information Encryption

Abstract

Abstract Increasing the number of optical information encryption (OIE) layers can exponentially enhance its security, which requires introducing additional degrees of freedom (DoFs) for light. However, traditional OIE systems encounter challenges due to exponential increases in volume and mass with the expansion of modulation DoFs, thereby retarding the development of integrated high‐security OIE. Here, a high‐dimensional dual‐layer OIE (DLOIE) strategy is proposed and experimentally established by utilizing a novel metasurface‐generated beam, termed spin‐multiplexed and grafted perfect vector vortex beam (MGPVVB). MGPVVB is generated by superposing grafted perfect vortex beams with programmable combinations of topological charges (CTCs) across two orthogonally circularly polarized states. As a key factor for DLOIE, MGPVVB introduces a new DoF called CTCs which can be customized within the same polarization order (PO). The metasurface is well‐suited for generating MGPVVBs over a wide bandwidth (450–1064 nm). MGPVVBs of all polarization states on the Poincaré sphere are generated. More importantly, DLOIE is achieved through an MGPVVB array. For DLOIE, information (true and false) encoding is based on PO and ellipticity, while verification of authenticity is governed by distinctive CTCs. This advancement enhances the security of OIE, and shows great value for applications in optical storage, optical communications, and quantum information processing.