Multiple degrees-of-freedom optical encryption via pixel-resolved vectorial holography

Optical encryption is pivotal to modern information security, however, conventional techniques mainly rely on the conjugated Fourier-transform relation between recording phase and retrieval information, making them vulnerable to iterative decryption attack. Although the synergy of multiple degrees of freedom (DoFs), such as optical metasurface platforms, offers a potential solution, the pixel-scale localized encrypting specific to confidential information (e.g., letters or patterns) remains elusive. To address this issue, we propose the vectorial optical pen to sketch optical foci for achieving pixel-resolved vectorial holograms. Moreover, the ciphertexts are simultaneously encoded by multiple DoFs, inherently resisting unauthorized access. Specifically, we convert the holographic plaintext (i.e., letters) to the ASCII codes for perfectly-matching the orthogonal polarization modes, yielding ultralow crosstalk and high security. The proposed dynamic and versatile system offers a practical route to high-capacity and high-confidentiality optical cryptography in the big-data era.