Monodomain Blue Phase Liquid Crystal Layers for Phase Modulation

Abstract

Liquid crystal “Blue Phases” (BP) have evolved, in the last years, from a scientific curiosity to emerging materials for new photonic and display applications. They possess attractive features over standard nematic liquid crystals, like submillisecond switching times and polarization- independent optical response. However, BPs still present a number of technical issues that prevent their use in practical applications: their phases are only found in limited temperature ranges, thus requiring stabilization of the layers; stabilized BP layers are inhomogeneous and not uniformly oriented, which worsen the optical performance of the devices. It would be essential for practical uses to obtain perfectly aligned and oriented monodomain BP layers, where the alignment and orientation of the cubic lattice are organized in a single 3D structure. In this work we have obtained virtually perfect monodomain BP layers and used them in devices for polarization independent phase modulation. We demonstrate that, under applied voltage, well aligned and oriented layers generate smoother and higher values of the phase shift than inhomogeneous layers, while preserving polarization independency. All BP devices were successfully stabilized in BPI phase, maintaining the layer monodomain homogeneity at room temperature, covering the entire area of the devices with a unique BP phase.

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.…”

Sculpted grain boundaries in soft crystals

“…Among liquid crystals, the so-called blue phases (BPs) are of particular interest as they share the properties of both a 3D cubic crystal and a liquid. Different strategies have been developed to produce BP monodomains, and these studies reveal that control of the BP lattice orientation and formation of dislocation-free macroscopic BP crystals are both particularly difficult to achieve (14)(15)(16)(17)(18). In this respect, the work by Zheng et al (18) represented an outstanding advance with respect to the control of the optical response of BPs, and they demonstrated a means of using light to produce rewriteable, on-demand patterns of BP monodomains.…”

Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry

“…Other kinds of optically isotropic mesophases observed in thermotropic liquid crystals are the so-called blue phases [21][22][23][24][25], characterized by a three-dimensional arrangement of cholesteric-like mesogen distribution, very low viscosity, fast molecular and collective dynamics. These low ordered optically isotropic mesophases are formed by chiral mesogens, and they are typically associated with the occurrence of higher ordered 'frustrated' LC phases, such as the twist grain boundaries (TGB) as well as the tetragonal phases [26].…”