Multi-Dimensional Meta-Holography Encrypted by Orbital Angular Momentum, Frequency, and Polarization

Metasurface holographic encryption, as an emerging and highly promising technique, presents the advantages of multi-dimension and high security and consequently provides a flexible and convenient platform for information encryption. Recent years have witnessed rapid progress in meta-holographic encryption through the utilization of different dimensions of electromagnetic (EM) waves, yet enhancing the capacity and security of encrypted information remains an endless goal. In this context, the concept of three physical dimensions encrypted metasurface holography is proposed in which orbital angular momentum (OAM) is fully synergized with frequency and polarization state. The mechanism relies on the simultaneous control of these dimensions and arbitrarily overlaying them in each operation channel, thereby acting as a multi-dimensional key to realize information encryption and decryption. As a proof-of-concept experiment, a three-physical dimension encrypted meta-hologram is designed that conceals four real images as encrypted information in 32 information channels. Remarkably, a specific OAM order, frequency, and polarization state is required to decrypt the designed meta-hologram. This work opens a new avenue for multi-dimensional encrypted holography, which has broad application prospects for information security and data storage in the era of big data.