Demonstration of patterned polymer-stabilized cholesteric liquid crystal textures for anti-counterfeiting two-dimensional barcodes

Li, Wensong; Shen, Yuan; Chen, Zhijie; Qian, Chao; Li, Sensen; Chen, Lujian

doi:10.1364/ao.56.000601

Cited by 47 publications

(37 citation statements)

References 27 publications

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“…Chen and co‐workers demonstrated patterned textures for anticounterfeiting using cholesteric liquid crystals. [ 127 ] Figure 16c shows the polarizing optical microscope (POM) images and illustrated schemes of switchable textures of the cholesteric liquid crystal under different voltages. Planar textures were observed without any external electric field.…”

Section: Strategies For Anticounterfeiting Via Structural Colorsmentioning

confidence: 99%

Structural Color Materials for Optical Anticounterfeiting

Hong

Yuan

Chen

2020

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303

251

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The counterfeiting of goods is growing worldwide, affecting practically any marketable item ranging from consumer goods to human health. Anticounterfeiting is essential for authentication, currency, and security. Anticounterfeiting tags based on structural color materials have enjoyed worldwide and long‐term commercial success due to their inexpensive production and exceptional ease of percept. However, conventional anticounterfeiting tags of holographic gratings can be readily copied or imitated. Much progress has been made recently to overcome this limitation by employing sufficient complexity and stimuli‐responsive ability into the structural color materials. Moreover, traditional processing methods of structural color tags are mainly based on photolithography and nanoimprinting, while new processing methods such as the inkless printing and additive manufacturing have been developed, enabling massive scale up fabrication of novel structural color security engineering. This review presents recent breakthroughs in structural color materials, and their applications in optical encryption and anticounterfeiting are discussed in detail. Special attention is given to the unique structures for optical anticounterfeiting techniques and their optical aspects for encryption. Finally, emerging research directions and current challenges in optical encryption technologies using structural color materials is presented.

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Section: Strategies For Anticounterfeiting Via Structural Colorsmentioning

confidence: 99%

Structural Color Materials for Optical Anticounterfeiting

Hong

Yuan

Chen

2020

Small

303

251

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“…These multidomain structures were found to produce special diffraction patterns. Recently, they have demonstrated 2D bar codes (Figure E,F) using CLC films where adjacent domains with vertical and horizontal helical axis orientation coexist . The unclonable bar codes were fabricated using the two‐step polymer stabilization of the CLC film.…”

Section: Control Of the Helical Axis Of Clcs By Different Stimulimentioning

confidence: 99%

Stimuli‐Driven Control of the Helical Axis of Self‐Organized Soft Helical Superstructures

2018

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Supramolecular and macromolecular functional helical superstructures are ubiquitous in nature and display an impressive catalog of intriguing and elegant properties and performances. In materials science, self-organized soft helical superstructures, i.e., cholesteric liquid crystals (CLCs), serve as model systems toward the understanding of morphology- and orientation-dependent properties of supramolecular dynamic helical architectures and their potential for technological applications. Moreover, most of the fascinating device applications of CLCs are primarily determined by different orientations of the helical axis. Here, the control of the helical axis orientation of CLCs and its dynamic switching in two and three dimensions using different external stimuli are summarized. Electric-field-, magnetic-field-, and light-irradiation-driven orientation control and reorientation of the helical axis of CLCs are described and highlighted. Different techniques and strategies developed to achieve a uniform lying helix structure are explored. Helical axis control in recently developed heliconical cholesteric systems is examined. The control of the helical axis orientation in spherical geometries such as microdroplets and microshells fabricated from these enticing photonic fluids is also explored. Future challenges and opportunities in this exciting area involving anisotropic chiral liquids are then discussed.

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“…The first approach to stabilize DGs consists in the formation of a polymer network by in situ photoinduced cross‐polymerization . For this purpose, a low‐molar‐mass cholesteric mixture is doped with a small amount (usually in the region of a few percent) of aliphatic or liquid crystalline diacrylate (often nematic diacrylate 8 or RM257, see Figure a) and a photoinitiator.…”

Section: Diffraction Structures In Clc Materials Induced By Electric mentioning

confidence: 99%

“…f) POM image of QR‐code inscribed by patterning of cholesteric DG of DM types. Black and bright regions correspond to the areas with homeotropic alignment and with DM grating, respectively . a–c) Reproduced with permission .…”

Section: Diffraction Structures In Clc Materials Induced By Electric mentioning

confidence: 99%

“…As a result, the linear pattern of alternated GM and DM(⊥) gratings was obtained as depicted in Figure e. A similar approach was used to create 2D pattern, in particular QR‐code (Figure f), which makes cholesteric DGs prospective in terms of their applicability for secure authentication or anti‐counterfeiting optical devices …”

Section: Diffraction Structures In Clc Materials Induced By Electric mentioning

confidence: 99%

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Cholesteric Liquid Crystal Materials for Tunable Diffractive Optics

Ryabchun

Bobrovsky

2018

Advanced Optical Materials

185

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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Demonstration of patterned polymer-stabilized cholesteric liquid crystal textures for anti-counterfeiting two-dimensional barcodes

Cited by 47 publications

References 27 publications

Structural Color Materials for Optical Anticounterfeiting

Structural Color Materials for Optical Anticounterfeiting

Stimuli‐Driven Control of the Helical Axis of Self‐Organized Soft Helical Superstructures

Cholesteric Liquid Crystal Materials for Tunable Diffractive Optics

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