Light-reconfigured waveband-selective diffraction device enabled by micro-patterning of a photoresponsive self-organized helical superstructure

Sun, Peizhi; Liu, Zhen; Wang, Wei; Ma, Lingling; Shen, Dong; Hu, Wei; Lu, Yan‐qing; Chen, Lujian; Zheng, Zhigang

doi:10.1039/c6tc02443b

Cited by 34 publications

(32 citation statements)

References 38 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%

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%

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 first approach is based on phototuning of the cholesteric pitch value by photoinduced changing of the HTP of the chiral‐photochromic dopant. Despite the fact that this phenomenon is well studied in numerous papers starting from mid 1990s as discussed in the first chapter, it was only recently applied for the fabrication of DGs . Alternatively, helix pitch could be photochemically modified by the photoisomerization of the nonchiral photochromic dopants .…”

Section: Light‐generated Cholesteric Dgsmentioning

confidence: 99%

“…d) Chemical structure of chiral‐photochromic dopant (11) and microstructures of a Fresnel zone plate, written with a patterned visible light after UV‐irradiation of the film. On bottom, the conspicuous focuses corresponding to the incident right‐handed (ii) and left‐handed (iii) circular polarized light (650 nm) . e) Chemical structure of azo‐dye (12).…”

Section: Light‐generated Cholesteric Dgsmentioning

confidence: 99%

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Cholesteric Liquid Crystal Materials for Tunable Diffractive Optics

Ryabchun

Bobrovsky

2018

Advanced Optical Materials

196

106

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refractive, diffraction and optical fiber components. In particular, diffraction grating (DG) is one of the key elements for the design and creation of modern optoelectronic devices. One of the most prominent materials for the creation of DGs is liquid crystals. The main feature of these systems is that liquid crystals combine properties such as optical anisotropy inherent for crystals and molecular mobility. High sensitivity to an external field, in particular to an electric field, makes liquid crystals very useful for the creation of DGs with tunable properties. The combination of these properties enables easy control of optical characteristics of such systems and opens wide perspectives for the design of new materials for diffractive optics.Among the different types of liquid crystalline (LC) phases, cholesteric liquid crystal (CLC) phase possesses intrinsic periodicity in the form of the helical supramolecular structure (Figure 1). With the realization of definite alignment conditions, this periodicity has been exploited for generation of DGs. [8,9] Another remarkable feature of the cholesteric mesophase is selective light reflection with the reflection wavelength determined by the simple Equation (1) where n is the average refractive index, and P is the helix pitch. The specific value of helix pitch depends on the chemical structure of the molecules forming the cholesteric phase and concentration of chiral moieties. One of the easiest ways to obtain the cholesteric mesophase is by doping the nematic matrix with chiral components (Figure 1). Variation of structure of chiral molecules by external stimuli leading, for examples, to the photoisomerization, is effectively used for fine tuning of the helix pitch. [10][11][12][13][14][15][16][17] In addition, the application of an electric field also provides a convenient opportunity to change optical properties of the CLC phase. [18][19][20][21] These unique properties enable to design a great variety of optical elements and devices based on CLC layers, films, or cells. Among them it is necessary to mention the media for photo-optical data recording, [22][23][24][25] electrically switchable mirrors, [26,27] optically controllable linearpolarization rotators, [28] coatings with controllable friction and adhesion, [29] materials for display technology, [23,30] secure Modern optics and photonics constantly require break-through materials and designs in order to achieve miniature, lightweight, highly tunable, and effective optical devices. One of the basic optical components is the diffraction grating (DG), widely used for the dispersion of light, beam steering, etc. This review gathers research efforts on diffractive optical elements based on cholesteric liquid crystal (CLC) materials with a supramolecular helical architecture. All main types and fabrication approaches of periodic diffractive structures from CLCs are classified and described. Key optical properties of DGs, their advantages and drawbacks are considered. Special attention is paid on the tunability of DG...

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“…[265] The sample, which was mixed with a small amount of a reactive monomer, was photopolymerized prior to being exposed to a 532 nm laser through a periodic photomask. [265] The sample, which was mixed with a small amount of a reactive monomer, was photopolymerized prior to being exposed to a 532 nm laser through a periodic photomask.…”

Section: Light-switched Cholesteric Lc Gratingmentioning

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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Light-reconfigured waveband-selective diffraction device enabled by micro-patterning of a photoresponsive self-organized helical superstructure

Abstract: A waveband-selective diffraction device was developed by micro-patterning of a photoresponsive self-organized helical liquid crystal superstructure.

Cited by 34 publications

References 38 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

Cholesteric Liquid Crystal Materials for Tunable Diffractive Optics

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

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