Fabrication and characterization of gratings based on thermal shrinkable reactive cholesteric mesogens

Gratings were successfully fabricated by photolithography by using a particular reactive cholesteric liquid crystal at two different temperatures. The reflection band of the grating was found to be wider than that of a film having a single helical order, because the grating exhibited a binary helical order. Moreover, the surface topography of the grating was regulated by using photomasks with different pitches. The optical reflection spectrum of this grating structure spans two reflection spectra of cholesteric liquid crystal films that were prepared by UV curing at two heating temperatures. Experimental results reveal that the method proposed in this study can be used to produce broadband circular polarizing films.