scholarly journals Light-Driven Pitch Tuning of Self-Assembled Hierarchical Gratings

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 326
Author(s):  
Yuan-Hang Wu ◽  
Sai-Bo Wu ◽  
Chao Liu ◽  
Qing-Gui Tan ◽  
Rui Yuan ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Soft Matter ◽  
Cholesteric Liquid Crystal ◽  
Functional Materials ◽  
Wave Pattern ◽  
Photonic Devices ◽  
Archimedean Spiral ◽  
First Order ◽  
Diffraction Angle ◽  
Self Assembled

Gratings are of vital importance in modern optics. Self-assembled cholesteric liquid crystal (CLC) gratings have attracted intensive attention due to their easy fabrication and broad applications. However, simultaneously achieving arbitrary patterning and delicate tuning of CLC gratings remains elusive. Here, light-driven pitch tuning is accomplished in hierarchical gratings formed in a molecular switch doped CLC. We fabricate a checkerboard hierarchical CLC grating for a demonstration, whose pitch is optically tuned from 4.6 µm to 10.7 µm. Correspondingly, the first-order diffraction angle continuously changes from 9.4° to 4.8° and a significant polarization selectivity is also observed. In addition, hierarchical CLC gratings with triangular wave pattern, Archimedean spiral, and radial stripes are also demonstrated. This work creates new opportunities for soft-matter-based intelligent functional materials and advanced photonic devices.

Topological liquid crystal superstructures as structured light lasers

2021 ◽  
Vol 118 (49) ◽  
pp. e2110839118
Author(s):  
Miha Papič ◽  
Urban Mur ◽  
Kottoli Poyil Zuhail ◽  
Miha Ravnik ◽  
Igor Muševič ◽  
...  
Keyword(s):  
Self Assembly ◽  
Soft Matter ◽  
Structured Light ◽  
Topological Defects ◽  
Photonic Devices ◽  
Light Polarization ◽  
Self Healing ◽  
Fabry Perot ◽  
Self Assembled ◽  
External Stimuli

Liquid crystals (LCs) form an extremely rich range of self-assembled topological structures with artificially or naturally created topological defects. Some of the main applications of LCs are various optical and photonic devices, where compared to their solid-state counterparts, soft photonic systems are fundamentally different in terms of unique properties such as self-assembly, self-healing, large tunability, sensitivity to external stimuli, and biocompatibility. Here we show that complex tunable microlasers emitting structured light can be generated from self-assembled topological LC superstructures containing topological defects inserted into a thin Fabry–Pérot microcavity. The topology and geometry of the LC superstructure determine the structuring of the emitted light by providing complex three-dimensionally varying optical axis and order parameter singularities, also affecting the topology of the light polarization. The microlaser can be switched between modes by an electric field, and its wavelength can be tuned with temperature. The proposed soft matter microlaser approach opens directions in soft matter photonics research, where structured light with specifically tailored intensity and polarization fields could be designed and implemented.

scholarly journals Periodic assembly of nanoparticle arrays in disclinations of cholesteric liquid crystals

2017 ◽  
Vol 114 (9) ◽  
pp. 2137-2142 ◽  
Author(s):  
Yunfeng Li ◽  
Elisabeth Prince ◽  
Sangho Cho ◽  
Alinaghi Salari ◽  
Youssef Mosaddeghian Golestani ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Self Assembly ◽  
Soft Matter ◽  
Cholesteric Liquid Crystal ◽  
Topological Defects ◽  
Spatial Inhomogeneity ◽  
Cholesteric Phase ◽  
Anisotropic Surface ◽  
Linear Defects

An important goal of the modern soft matter science is to discover new self-assembly modalities to precisely control the placement of small particles in space. Spatial inhomogeneity of liquid crystals offers the capability to organize colloids in certain regions such as the cores of the topological defects. Here we report two self-assembly modes of nanoparticles in linear defects-disclinations in a lyotropic colloidal cholesteric liquid crystal: a continuous helicoidal thread and a periodic array of discrete beads. The beads form one-dimensional arrays with a periodicity that matches half a pitch of the cholesteric phase. The periodic assembly is governed by the anisotropic surface tension and elasticity at the interface of beads with the liquid crystal. This mode of self-assembly of nanoparticles in disclinations expands our ability to use topological defects in liquid crystals as templates for the organization of nanocolloids.

scholarly journals Molecular ejection transition in liquid crystal columns self-assembled from wedge-shaped minidendrons

Soft Matter ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 22-29 ◽  
Author(s):  
William S. Fall ◽  
Ming-Huei Yen ◽  
Xiangbing Zeng ◽  
Liliana Cseh ◽  
Yongsong Liu ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Statistical Modelling ◽  
First Order ◽  
Self Assembled

A first-order mesophase transition between 4-dendron and 3-dendron columns, resulting from temperature-induced molecular ejection, is discovered and explained via statistical modelling.

scholarly journals Construction of Functional Materials in Various Material Forms from Cellulosic Cholesteric Liquid Crystals

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2969
Author(s):  
Kazuma Miyagi ◽  
Yoshikuni Teramoto
Keyword(s):  
Liquid Crystal ◽  
Physicochemical Properties ◽  
Mesoporous Materials ◽  
Cellulose Nanocrystals ◽  
Cholesteric Liquid Crystal ◽  
Functional Materials ◽  
Cellulose Derivatives ◽  
Sustainable Society ◽  
Wide Range ◽  
Material Form

Wide use of bio-based polymers could play a key role in facilitating a more sustainable society because such polymers are renewable and ecofriendly. Cellulose is a representative bio-based polymer and has been used in various materials. To further expand the application of cellulose, it is crucial to develop functional materials utilizing cellulosic physicochemical properties that are acknowledged but insufficiently applied. Cellulose derivatives and cellulose nanocrystals exhibit a cholesteric liquid crystal (ChLC) property based on rigidity and chirality, and this property is promising for constructing next-generation functional materials. The form of such materials is an important factor because material form is closely related with function. To date, researchers have reported cellulosic ChLC materials with a wide range of material forms—such as films, gels, mesoporous materials, and emulsions—for diverse functions. We first briefly review the fundamental aspects of cellulosic ChLCs. Then we comprehensively review research on cellulosic ChLC functional materials in terms of their material forms. Thus, this review provides insights into the creation of novel cellulosic ChLC functional materials based on material form designed toward the expanded application of cellulosics.

scholarly journals Overlooked Ionic Phenomena Affecting the Electrical Conductivity of Liquid Crystals

2021 ◽  
Vol 11 (1) ◽  
pp. 1
Author(s):  
David Webb ◽  
Yuriy Garbovskiy
Keyword(s):  
Electrical Conductivity ◽  
Liquid Crystal ◽  
Liquid Crystals ◽  
Physical Properties ◽  
Soft Matter ◽  
Photonic Devices ◽  
Optical Components ◽  
Dynamically Reconfigurable ◽  
Liquid Crystal Devices ◽  
New Applications

Liquid crystal devices, such as displays, various tunable optical components, and sensors, are becoming increasingly ubiquitous. Basic physical properties of liquid crystal materials can be controlled by external physical fields, thus making liquid crystal devices dynamically reconfigurable. The tunability of liquid crystals offers exciting opportunities for the development of new applications, including advanced electronic and photonic devices, by merging the concepts of flat optics, tunable metasurfaces, nanoplasmonics, and soft matter biophotonics. As a rule, the tunability of liquid crystals is achieved by applying an electric field. This field reorients liquid crystals and changes their physical properties. Ions, typically present in liquid crystals in minute quantities, can alter the reorientation of liquid crystals through the well-known screening effect. Because the electrical conductivity of thermotropic liquid crystals is normally caused by ions, an understanding of ion generation processes in liquid crystals is of utmost importance to existing and emerging technologies relying on such materials. That is why measuring of electrical conductivity of liquid crystals is a standard part of their material characterization. Measuring the electrical conductivity of liquid crystals is a very delicate process. In this paper, we discuss overlooked ionic phenomena caused by interactions of ions with substrates of the liquid crystal cells. These interactions affect the measured values of the DC electrical conductivity of liquid crystals and make them dependent on the cell thickness.

Polymer Stabilized Bistable Dual Frequency Cholesteric Liquid Crystal Devices Assisted by a Predesigned Chiral Dopant

2021 ◽  
Author(s):  
Chun-Yen Liu ◽  
Chi-Feng Yen ◽  
Yi-Hua Hung ◽  
Chia-Ming Tu ◽  
Guan-Yi Wu ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Cholesteric Liquid Crystal ◽  
Photonic Devices ◽  
Smart Devices ◽  
Dual Frequency ◽  
External Stimulation ◽  
Liquid Crystal Devices ◽  
Polymer Stabilized

Liquid crystals have great potential for developing photonic devices that control the optical behaviors of liquid crystals in smart devices with external stimulation. In this study, we demonstrated a series...

scholarly journals Tuneable multicoloured patterns from photonic cross-communication between cholesteric liquid crystal droplets

2014 ◽  
Vol 2 (5) ◽  
pp. 806-810 ◽  
Author(s):  
JungHyun Noh ◽  
Hsin-Ling Liang ◽  
Irena Drevensek-Olenik ◽  
Jan P. F. Lagerwall
Keyword(s):  
Liquid Crystal ◽  
Photonic Crystals ◽  
Cholesteric Liquid Crystal ◽  
Self Assembled

Cholesteric liquid crystal droplets are self-assembled spherical photonic crystals. Multiple droplets in the same plane communicate optically, giving rise to unique patterns of circularly polarised and strongly coloured spots. We explain the phenomenon and outline routes to application.

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