Electrically tunable photonic band gap structure in monodomain blue-phase liquid crystals

Abstract

Photonic band gap materials have the ability to modulate light. When they can be dynamically controlled beyond static modulation, their versatility improves and they become very useful in scientific and industrial applications. The quality of photonic band gap materials depends on the tunable wavelength range, dynamic controllability, and wavelength selectivity in response to external cues. In this paper, we demonstrate an electrically tunable photonic band gap material that covers a wide range (241 nm) in the visible spectrum and is based on a monodomain blue-phase liquid crystal stabilized by nonmesogenic and chiral mesogenic monomers. With this approach, we can accurately tune a reflection wavelength that possesses a narrow bandwidth (27 nm) even under a high electric field. The switching is fully reversible owing to a relatively small hysteresis with a fast response time, and it also shows a wider viewing angle than that of cholesteric liquid crystals. We believe that the proposed material has the potential to tune color filters and bandpass filters.

All-Optically Controllable Photonic Crystals Based on Chiral-Azobenzene-Doped Blue Phase Liquid Crystals

“…The valid reflection spectra of BPI can be obtained from 48.6 • C to 45.8 • C, at which the reflection peak red-shifts from 550 nm to 629 nm. Here, the strong anisotropic anchoring force from the surface alignment can result in a more uniform formation of the BP crystal structure in the aligned BP cell, which can also be found in previous studies [28][29][30][31][32][33][34][35]. In addition to BPI, the complete BPII and BPS-like phase can be effectively induced by the anisotropic anchoring force from the surface alignment [32,36], thereby extending the entire BP temperature range of the aligned sample.…”

3D Chiral Photonic Nanostructures Based on Blue‐Phase Liquid Crystals

“…Compared with lattice distortion, field‐induced phase transition requires a much higher electric field strength and usually results in an irreversible and discontinuous shift in selective reflections. [ 149–153 ]…”

Alignment Layer of Liquid Crystal Using Plant-Based Isoeugenol-Substituted Polystyrene

“…For example, LC molecules such as transmissive LCs, nematic LCs, reflective LCs, and cholesteric LCs have been widely used in the display industry [ 60 ]. Technologies to align LC molecules in the same direction on a substrate can be used in a variety of fields such as chemistry [ 61 ], physics [ 62 ], biology [ 63 ], and nanotechnology [ 64 ], by inducing interactions between LC molecules and surfaces on the substrate. Mechanical rubbing is a common method used to produce uniform orientation of LC molecules [ 65 ].…”