Touch-Driven Bi-Chiral Superstructures for Nested Encryption of Multiplexed Optical Information

With the growing demand for data security, optical encryption has emerged as a promising solution due to its high-speed, parallel and low-power-consumption characteristics. However, most optical encryption methods rely on static structures involved with only few optical degrees of freedom (DOFs), resulting in simple encryption methods susceptible to attacks. Herein, a dynamic nested optical encryption scheme is proposed using a touch-driven bi-chiral cholesteric liquid crystal (CLC) superstructure, where relief-structured polymerized CLCs are combined with temperature-sensitive opposite-handed CLCs. Through delicate photopatterning and Bragg reflection engineering, independent geometric phases can be induced to the reflected light with orthogonal circular polarization and multiple wavelengths. Thus, various optical DOFs (wavelength, amplitude, and polarization) and environmental factors (temperature or human-device interaction) are encoded as different encryption dimensions. Based on the developed four-step encryption algorithm, the four-level nested encryption is demonstrated by multiplexing the plaintext and multilevel ciphertexts in structural colors, multicolored vectorial holography and their temperature-driven variations. The plaintext can be derived only through a specific order, with the final step completed by a human touch. This work advances the on-demand construction of chiral nanostructures, and offers a new paradigm for high-security and high-capacity optical informatics.