Generating Switchable and Reconfigurable Optical Vortices via Photopatterning of Liquid Crystals

Wei, Bingyan; Hu, Wei; Ming, Yang; Xu, Fei; Rubin, Shimon; Wang, Jianguo; Chigrinov, Vladimir G.; Lu, Yanqing

doi:10.1002/adma.201305198

Cited by 173 publications

(116 citation statements)

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“…[19] The light-triggered deformation of an LCN actuator is governed by the alignment distribution of the constituent liquid-crystal molecules within the polymer network, and developing methods for precise control over the director distribution in order to obtain desired photoactuation mode is an important topic of research. [14,[20][21][22] Photoalignment has proven to be a successful technique in patterning complex alignments into liquid-crystalline materials [23][24][25] and in devising on-demand actuations into LCNs. [21] The technique is based on illuminating a thin photoresponsive layer, a "command surface," [26] with linearly polarized light.…”

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confidence: 99%

Programming Photoresponse in Liquid Crystal Polymer Actuators with Laser Projector

Wani

Zeng

Wasylczyk

et al. 2017

Advanced Optical Materials

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have emerged as promising materials for fabricating soft actuators. [12][13][14] LCNs combine the anisotropy of the constituent liquid-crystal (LC) molecules and the elasticity of polymer networks, and are capable of stimuli-responsive shape change at the macroscopic scale. LCNs can be actuated by various stimuli such as light, [15] heat, [16] solvent, [17] and humidity. [18] Being a clean, remote, and precisely controllable stimulus, light is a particularly attractive energy source. [19] The light-triggered deformation of an LCN actuator is governed by the alignment distribution of the constituent liquid-crystal molecules within the polymer network, and developing methods for precise control over the director distribution in order to obtain desired photoactuation mode is an important topic of research. [14,[20][21][22] Photoalignment has proven to be a successful technique in patterning complex alignments into liquid-crystalline materials [23][24][25] and in devising on-demand actuations into LCNs. [21] The technique is based on illuminating a thin photoresponsive layer, a "command surface," [26] with linearly polarized light. Upon illumination, the photoalignment layer becomes anisotropic, thereby changing the boundary conditions experienced by the liquid-crystal molecules in the vicinity, and forcing them to align either perpendicular [27] or parallel [28] to the light polarization. Photopatterning of director orientation can be achieved by spatially modulating the light polarization, [27] or exposure through mask(s). [28,29] White and co-workers have used a laser setup to raster scan a focussed laser beam with controlled polarization across the sample, and thus achieved local control in the director distribution. [30][31][32] Also spatial light modulators and digital micromirror devices have been used for high-throughput patterning. [17,[33][34][35] These demonstrations require either prepatterned masks or relatively complex optical set-ups for programming the desired director distribution.Herein, we use a laser projector with a microelectromechanical system (MEMS)-based scanning mirror assembly (PICO, Sony) to program the liquid-crystal alignment within a monolithic LCN film. Photopatterning is achieved by projecting an arbitrary computer-generated image onto the photoalignment layer, using predefined light polarization. The projector is capable of addressing a minimum feature size of 50 µm over an area of 25 × 14 mm 2 . A series of complex photoactuators, such as defect buckling, coiling strip with gradient in pitch, four-arm gripper, and bidirectional bending in an octopod, are demonstrated by engineering different director orientations via photopatterning. The photoactuators are fabricated by polymerizing LC monomer mixtures inside LC cells that have been A versatile, laser-projector-based method is demonstrated for programming alignment patterns into monolithic films of liquid crystal polymer networks. Complex images can be photopatterned into the polymer films with sub-100 µm resolution, using relative...

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confidence: 99%

Programming Photoresponse in Liquid Crystal Polymer Actuators with Laser Projector

Wani

Zeng

Wasylczyk

et al. 2017

Advanced Optical Materials

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“…24 In this work, we investigate the PSHE via light-matter interaction in LC-based twisting structures which are made through the photoalignment technique. 25,26 The physical mechanism of such a system is discussed in detail. The light-matter interaction in the LC medium is described by the Maxwell-Schrödinger equation, 27,28 and the interaction Hamiltonian is obtained and shown to be similar with those of the Rashba and Dresselhaus types of electronic systems.…”

Section: Introductionmentioning

confidence: 99%

“…The light-matter interaction in the LC medium is described by the Maxwell-Schrödinger equation, 27,28 and the interaction Hamiltonian is obtained and shown to be similar with those of the Rashba and Dresselhaus types of electronic systems. Owing to the photoalignment technique, it is convenient to control the LC directors locally, 25,26 and thus the spin-orbit interaction process in the LC twisting structures can be flexibly tailored to present various PSHE phenomena. As regards the experimental verification, we prepare several representative samples, and the obtained results are consistent with our theoretical analyses.…”

Section: Introductionmentioning

confidence: 99%

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Tailoring the photon spin via light–matter interaction in liquid-crystal-based twisting structures

Ming

Chen

et al. 2017

npj Quant Mater

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We demonstrate the photonic spin Hall effect in a system comprising designable liquid crystal materials. The photoalignment technique provides an effective approach to control the directors of the liquid crystal molecules. Twisting structures with different transverse distributions are conveniently introduced into the liquid crystal plates for tailoring the spin-orbit coupling process to present various photonic spin Hall effect phenomena. The light-matter interaction in the twisting mediums is described with a Schrödinger-like equation. The photonic spin Hall effect considered in the study is explained as the result of an effective magnetic field acting on a pseudospin. Moreover, owing to the designability of the liquid crystal system, it is a potential platform for Hamiltonian engineering. Several valuable multiple quantum systems are possible to be presented in classical analogies.npj Quantum Materials (2017) 2:6 ; doi:10.1038/s41535-017-0011-1 INTRODUCTIONSpintronics becomes an attractive field of condensed matters in recent years and shows its immense potential in quantum information applications.1, 2 Various spintronic devices have been demonstrated to play important roles in quantum information processing and quantum computation.3, 4 The central theme of spintronics is manipulation of the spin degrees of freedom. The spin Hall effect (SHE) provides an effective approach for controlling the electron spin, and a large number of interesting investigations have been demonstrated. 5,6 Although considerable progress has been made, the electronic systems always face the problem of decoherence and decay. 7 In this aspect, the photonic quantum system has obvious advantages. Moreover, the photon is also an ideal spin carrier. The discovery of photonic spin Hall effect (PSHE) provides a powerful approach for controlling and manipulating the spin photons.8 Therefore, the photonic systems can be alternative choices for designing spin-based devices, thus raising an increasing research interest.

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“…Recent efforts in aligning LC molecules into spatially non-uniform orientation patterns have led to many new liquid crystal devices and applications, such as beam steering [1,2], q-plates [3][4][5][6], geometric phase wave plates [7,8], programmable origamis [9][10][11][12], controlled placement and assembly of particles [13][14][15][16], predesigned microfluidic electrokinetic flows in LCs [17,18], and command of active matter [19]. One technique is based on photoalignments through pixel-by-pixel direct laser writing [11,20].…”

Section: Introductionmentioning

confidence: 99%

Designs of Plasmonic Metamasks for Photopatterning Molecular Orientations in Liquid Crystals

et al. 2016

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Aligning liquid crystal (LC) molecules into spatially non-uniform orientation patterns is central to the functionalities of many emerging LC devices. Recently, we developed a new projection photopatterning technique by using plasmonic metamasks (PMMs), and demonstrated high-resolution and high-throughput patterning of molecular orientations into arbitrary patterns. Here we present comparisons between two different types of metamask designs: one based on curvilinear nanoslits in metal films; the other based on rectangular nanoapertures in metal films. By using numerical simulations and experimental studies, we show that the PMMs based on curvilinear nanoslits exhibit advantages in their broadband and high optical transmission, while face challenges in mask designing for arbitrary molecular orientations. In contrast, the PMMs based on nanoapertures, though limited in optical transmission, present the great advantage of allowing for patterning arbitrary molecular orientation fields.

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Generating Switchable and Reconfigurable Optical Vortices via Photopatterning of Liquid Crystals

Cited by 173 publications

References 46 publications

Programming Photoresponse in Liquid Crystal Polymer Actuators with Laser Projector

Programming Photoresponse in Liquid Crystal Polymer Actuators with Laser Projector

Tailoring the photon spin via light–matter interaction in liquid-crystal-based twisting structures

Designs of Plasmonic Metamasks for Photopatterning Molecular Orientations in Liquid Crystals

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