ABSTRACT We report a heliconical cholesteric liquid crystal () system that exhibits electrically tunable, multi‐order Bragg reflections spanning from the ultraviolet to near‐infrared range. The system is composed of a binary mixture of a flexible dimer (CB7CB) and rod‐like nematic liquid crystal (E7), doped with a left‐handed chiral compound. The heliconical structure supports simultaneous reflections at both the full‐pitch () and half‐pitch () periodicities, with distinct polarizati characteristics: the ‐order reflection yields linearly polarized light, whereas the ‐order produces circularly polarized reflection. Notably, these optical features are observable even under normal light incidence, in contrast to prior reports requiring oblique geometries. Furthermore, robust and reversible tuning of both reflection wavelength and polarization state is achieved via low‐voltage electric fields across a range of surface alignments, including untreated substrates. The system also displays a previously unreported two‐stage reflection behavior and hysteresis under increasing and decreasing electric fields. These findings highlight a versatile, alignment‐independent approach to field‐tunable photonic materials with potential applications in reflective displays, smart windows, and polarization‐multiplexed devices.
Sung et al. (Thu,) studied this question.