The remarkable progress in photoalignment technology has greatly propelled the development of planar liquid crystal devices based on the Pancharatnam-Berry (PB) phase. Currently, by leveraging properties such as birefringence and optical rotatory dispersion of liquid crystal molecules, along with tailored micro-/nano-structural designs, these planar devices can achieve multidimensional multiplexing functions, including spatial, polarization, wavelength, and angular multiplexing. Nevertheless, significant opportunities remain to further enhance their information capacity and the number of multiplexing channels.

This study proposes and experimentally validates a novel multidimensional multiplexing holographic image encryption method based on liquid crystal photoalignment. Central to our approach is the fabrication of planar liquid crystal optical elements via a single-step exposure process enabled by a liquid crystal spatial light modulator (LC-SLM). Compared with conventional multi-step lithography techniques, this method substantially simplifies the manufacturing process. Within a single device, we exploit three independent physical dimensions for information encoding and encryption. First, polarization multiplexing is achieved by leveraging the orientational degeneracy of liquid crystal molecules in accordance with Malus’s law, enabling independent encoding of two binary images in the near field. Second, spatial position multiplexing is realized through a modified Gerchberg-Saxton (GS) algorithm based on Fresnel diffraction theory, allowing distinct images to be reconstructed at predetermined propagation distances. Third, wavelength multiplexing is implemented by utilizing the dispersive relationship between reconstruction distance and incident wavelength, ensuring that specific images are retrievable only under illumination with their corresponding wavelength.

By integrating these three mechanisms, we successfully designed and fabricated a six-channel encryption system on a single planar liquid crystal element. This system comprises two near-field polarization channels and four far-field holographic channels, which combine both wavelength-multiplexed and position-multiplexed images. Experimental results demonstrate the successful and independent reconstruction of various target patterns, including alphanumeric characters and QR codes. Furthermore, to enhance security, we establish a nested encryption scheme that integrates this multidimensional physical encryption with the classical cryptographic algorithm-the Vigenère cipher. In this scheme, complete decryption requires simultaneous possession of multiple physical keys (correct wavelength, polarization state, and observation distance) along with the algorithmic key, thereby establishing a robust defense against partial information breaches.

In conclusion, this work not only confirms the feasibility and considerable potential of planar liquid crystal devices for high-capacity, multidimensional optical encryption but also provides a practical and integrated framework for its implementation. The proposed method—characterized by simplified fabrication, a high degree of integration, and enhanced security through physical-algorithmic nesting—paves the way for next-generation optical security systems. It holds promising application prospects in fields such as high-security information storage, anti-counterfeiting, and optical data encryption, offering a viable pathway toward safeguarding information against future computational threats.