Direct Laser Writing 3D Carbon Dot Array for Orbital Angular Momentum Holographic Encryption

Abstract Information security is crucial in modern society, spawning numerous cryptographic strategies to protect data from stealing and deciphering. Among them, optical encryption is an excellent candidate due to its unique features such as high‐speed parallel processing, low power consumption, and abundant degree of freedom. Despite recent advances of nanophotonic devices that have promoted the development of optical encryption techniques, the realization of high‐security and high‐capacity all‐optical 3D image encryption remains an ongoing challenge due to the absence of a suitable 3D nanophotonic device. Here, the study constructs an integrated 3D carbon dot (CD) array through direct laser writing (DLW) in a solid‐state polymeric material and demonstrate its parallel manipulation and selective transmission characteristics of multiple orbital angular momentum (OAM) beams. Benefitting from the photo‐luminescence responses of the CDs and theoretically unlimited helical mode indices of OAM beams, a high‐security and high‐capacity all‐optical encryption platform by integrating the 3D CD array and an OAM‐multiplexing hologram is developed. Through the platform, the encryption and decryption of a series of multi‐plane 3D images can be realized without additional digital post‐processing. The results provide a novel inspiration for nanophotonic devices‐based all‐optical encryption and advance the development of optical encryption applications harnessing light's OAM dimension.