Tunable Circular Diattenuation and Passive Optical Isolation in Dye-Doped Cholesteric Glassy Liquid Crystals

Abstract Cholesteric liquid crystals (CLCs) are well-known for selective reflection of circularly polarized light arising from their helical supramolecular structure. Cholesteric glassy liquid crystals (ChGLCs) preserve this helicoidal order through vitrification, making the associated chiroptical response accessible in a mechanically robust, solid-state film. Incorporation of guest chromophores that align with the liquid-crystalline director can produce differential absorption of circularly polarized light through chiral guest–host interactions. While this effect has been reported, it remains poorly quantified, and its translation to device-level functionality is underdeveloped. Here, we demonstrate that dye-doped ChGLCs give rise to quantifiable absorption-based circular diattenuation that can be controlled by variation of cholesteric pitch, film thickness, and dye concentration. Spectroscopic Mueller matrix ellipsometry directly resolves circular diattenuation that is absent in achiral hosts. An optical model based on an extended Good–Karali formulation captures polarization-resolved transmission and establishes design relationships linking structure to optical response. Guided by this framework, we design and experimentally validate a single-layer, passive optical isolator element operating via double-pass attenuation, in which forward transmission is permitted while retroreflected light is suppressed following polarization reversal upon reflection. These results establish dye-doped ChGLCs as a tunable platform for compact, absorption-based optical isolation.