Light-Controllable Electroconvection Patterns in a Chiral Nematic Liquid Crystal

Jing, Hongzhen; Xiang, Ying; Xu, Ming-Ya; Wang, Everett; Wang, Jing; Éber, Nándor; Buka, Ágnes

doi:10.1103/physrevapplied.10.014028

Cited by 12 publications

(8 citation statements)

References 49 publications

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“…So far, most PtLC materials and their applications have been realized by doping a standard LC with a separate photochromic dye . However, recently, novel PtLC materials comprising only a single component have been developed, in which every mesogenic molecule of LCs contains a photosensitive moiety .…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the introduction of a functional group that allows for the modulation of the properties of BCLCs by means of magnetic field or light is nowadays of eminent interest. UV light stimulus can stabilize blue phases; it may cause isothermal chirality switching which results in reversible phototuning of the wave vector of electroconvection patterns in cholesterics . Potential applications of BCLC materials, in particular those exhibiting a nematic phase (bent‐core nematics, BCNs), are foreseen in optical data storage, holographic media, photonics, or photoalignment of LC matrices, though they have not been realized yet.…”

Section: Introductionmentioning

confidence: 99%

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Light Tunable Gratings Based on Flexoelectric Effect in Photoresponsive Bent‐Core Nematics

Jing

Xiang

et al. 2019

Advanced Optical Materials

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A new photoresponsive bent‐core nematic (BCN) material, which exhibits flexoelectric domains (FDs) driven by electric field, is reported. Unexpectedly, it is found that the morphologies of FDs can be controlled by irradiation with light fields. This light tunability is ascribed to the photoisomerization effect of the azo moiety within the BCN molecules, where the ratio of trans and cis isomers changes according to the parameters of the light field, resulting in adjustable electric threshold and periodicity of FDs. Based on this principle, a prototype of controllable optical grating is assembeled, whose operation can be manipulated by the wavelength or intensity of light. Due to the easy, instant, and remote operation by light, this optical, contactless tunability has a great advantage over traditional electric control in tunable photonic devices.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Light Tunable Gratings Based on Flexoelectric Effect in Photoresponsive Bent‐Core Nematics

Jing

Xiang

et al. 2019

Advanced Optical Materials

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“…The switch promotes helix inversion under continuous UV irradiation, going from right handed to left handed during the exposition. [278] Upon UV irradiation, with the field maintained, the helix unwinds, passing through the nematic LC until it forms the LH texture with left handedness.…”

Section: Dual Stimuli-driven Cholesteric Lc Gratingsmentioning

confidence: 99%

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

et al. 2018

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the duality consolidation, the idea of controlling light and how it interacts with matter has always been an exciting topic. Visible light, as we perceive it, is a small portion of the electromagnetic spectrum composed of mutually perpendicular oscillating electric and magnetic fields that propagate through space and presents wave-like and particle-like behavior. Since the elements comprising matter possess dynamic electron clouds, the electromagnetic nature of light prompts different responses when it interacts with different materials, depending on its intensity, frequency, the arrangement of molecules, and so on. Whenever light interacts with matter, it might be absorbed, re-emitted, scattered, or transmitted. Although these effects are well known, the combination of them with new, innovative materials pushes optics forward. In fact, advances in optics have often occurred through the development of materials with improved optical properties, thus creating remarkable applications that tremendously influence our daily lives. These exciting applications include image processing and recording, lasing, data storage, display devices, detector systems, propulsion systems, and optical tweezers, which have enabled remote micromanipulation of colloidal particles and promising applications in various biomedical and biological applications. [1][2][3] There is, however, one component that stands out: the diffraction grating. It is generally regarded as one of the most important devices in the development of several fields of science. [4] Such importance comes from the fact that a diffraction grating is a device with a periodic structure capable of changing the propagation and splitting the spectrum The ability to control light direction with tailored precision via facile means is long-desired in science and industry. With the advances in optics, a periodic structure called diffraction grating gains prominence and renders a more flexible control over light propagation when compared to prisms. Today, diffraction gratings are common components in wavelength division multiplexing devices, monochromators, lasers, spectrometers, media storage, beam steering, and many other applications. Next-generation optical devices, however, demand nonmechanical, full and remote control, besides generating higher than 1D diffraction patterns with as few optical elements as possible. Liquid crystals (LCs) are great candidates for light control since they can form various patterns under different stimuli, including periodic structures capable of behaving as diffraction gratings. The characteristics of such gratings depend on several physical properties of the LCs such as film thickness, periodicity, and molecular orientation, all resulting from the internal constraints of the sample, and all of these are easily controllable. In this review, the authors summarize the research and development on stimuli-controllable diffraction gratings and beam steering using LCs as the active optical materials. Dynamic gratings fabricated by applying external f...

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“…[ 10,20,21 ] Other materials such as dyes, chiral dopant, nanoparticles, and nanotubes have also been explored as the dopant in nematic LCs for their impact on the corresponding EC phenomena. [ 22–25 ]…”

Section: Introductionmentioning

confidence: 99%

Electroconvection in Zwitterion‐Doped Nematic Liquid Crystals and Application as Smart Windows

Zhang

Yang

Zhan

et al. 2020

Advanced Optical Materials

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Electroconvection (EC) in liquid crystals (LCs) is extensively studied for the formation of regular nonequilibrium structures, and the applications that require strong light scattering and high haze. Doping the LCs with ionic species has proven to be an effective method to obtain uniform and high‐quality textures. Herein, zwitterion is explored as a new class of ionic dopant that has little problem of ion accumulation as compared to typical organic electrolytes. A rich variety of EC patterns are observed and characterized for both positive and negative LCs doped with a zwitterion Reichardt's dye. The initial homogeneous or homeotropic alignment, as well as the voltage and frequency of the applied electric field, is shown to influence the formation of EC patterns, among which the dynamic scattering mode (DSM) is specially examined for the application as privacy‐protecting smart windows. Using an LC mixture doped with zwitterions, the smart window demonstrates outstanding performance, as well as much improved durability for a wide range of operating conditions. Such a method offers a simple strategy for the fabrication of polymer‐free smart windows.

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Light-Controllable Electroconvection Patterns in a Chiral Nematic Liquid Crystal

Cited by 12 publications

References 49 publications

Light Tunable Gratings Based on Flexoelectric Effect in Photoresponsive Bent‐Core Nematics

Light Tunable Gratings Based on Flexoelectric Effect in Photoresponsive Bent‐Core Nematics

Dynamic Control of Light Direction Enabled by Stimuli‐Responsive Liquid Crystal Gratings

Electroconvection in Zwitterion‐Doped Nematic Liquid Crystals and Application as Smart Windows

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