Optical Encryption Based on Cascaded and Multi-Images Integrated Liquid Crystal Elements with High Security

We propose and demonstrate an optical encryption scheme based on cascaded photo-aligned liquid crystal (LC) elements with single-to-multi-image integration. Unlike conventional approaches relying on far-field holography, the proposed method utilizes near-field modulation to improve image capacitance. Theoretical analysis based on a modified Malus’s law provides several optimized orientation-angle distribution phases for optical encryption and decryption with single- or multi-image integrated into the encrypted phase. By employing these phases as LC orientation-angle distributions, corresponding LC elements were fabricated using our single-step exposure photoalignment system. Several independent target images can be reconstructed under different decrypted phases of the second LC element. Both simulations and experiments validate that the proposed scheme achieves a high quality of image reconstruction up to four integrated images. Furthermore, the impacts of LC phase mismatch and spatial misalignment were also investigated, showing that only small mistakes of phases (<20%) and positions (<0.08 mm, <0.2°) can lead to successful image reconstruction, making the system more secure. This work provides a framework for higher-capacity optical encryption and advanced photonic information processing.