Glassy Liquid Crystal Films as Broadband Polarizers and Reflectors via Spatially Modulated Photoracemization

Chiral-nematic glassy liquid crystals (GLCs) are of interest because of their unique supramolecular structure and associated optical properties. However, the constant-pitch films produced so far have a bandwidth limited to less than 100 nm in the visible. The introduction of a pitch gradient, indicated by theory to increase bandwidth, is reported here to be achieved by the generation of a pitch gradient in the mesomorphic fluid state and subsequent thermal quenching, freezing in the pitch gradient. An increase of polarization bandwidth by a factor of 2.4 was found.