Soft chiral superstructure enabled dynamic polychromatic holography

Planar optics offers a compact and versatile platform for manipulating multiple dimensions of light parameters and thus has attracted tremendous interest in high-density data storage, high-security information encryption, and holographic displays. It is still challenging to achieve active functionalities via dynamically operating light-matter interactions inside these planar optics. Here, a polymer-stabilized cholesteric liquid crystal (CLC) is adopted as a tunable one-dimensional chiral superstructure. The bandgap tends to change from a periodic helix to a gradient-pitch configuration under direct current (DC) voltage, and the reflection bandwidth varies from a narrow band of 40 nm to a broad band of 180 nm. Off-axis phase-only holograms of three primary colors are properly k-space engineered via a modified Gerchberg-Saxton algorithm, and recorded into the initial alignments of the CLC by photopatterning. By altering the applied DC voltage, the generated holography actively switches between a monochromatic and polychromatic image. Moreover, spin-selective Bragg-Berry phase encoding in photopatterned superstructures with opposite helicity allows distinct holograms (e.g., "weather sign" and "chameleon") to be independently generated and modulated. This work takes full advantage of soft chiral superstructures for on-demand light control and has great potential in dynamic holography, information encryption, and data storage.