Moiré Phase Mapping in Twisted Bilayer Liquid Crystals with Reconfigurable Light Polarization States.

Abstract

Liquid crystals are crystalline materials with only orientational orders without long-range positional orders, which have been broadly used in optical devices due to their capability in modulating light polarization. In developing practical optical devices, photolithography is widely used in patterning liquid crystals for sensing, anticounterfeiting, displays, and camouflage. These structures are fixed once made and creating dynamic multi-domain optical materials is challenging. Here, we report the development of dynamic moiré patterns by vertical stacking assembly of two liquid crystals having designer domains and optical properties. Magnetic Fe₃O₄ nanorods were used as building blocks and assembled into liquid crystals under a magnetic field, which is driven by the preferential alignment of nanorods' long axes to the field. Stacking two aligned nanorod films with controlled twist angles forms twisted bilayers that generate moiré superstructures in polarization space, producing angle-dependent trajectories on the Poincaré sphere. This work demonstrates spatially resolved Stokes parameters and twist-dependent photonic phases based on pixel-level mapping of light polarization states. These moiré-symmetry, twisted bilayer liquid crystals provide a route to active optical devices for dynamic photonic modulation, polarization filtering, and polarization-encoded anticounterfeiting.