Fringing-field minimization in liquid-crystal-based high-resolution switchable gratings

Gu, Lanlan; Chen, Xiaonan; Jiang, Wei; Howley, Brie; Chen, Ray T.

doi:10.1063/1.2130729

Cited by 35 publications

(25 citation statements)

References 10 publications

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“…First, by exploiting striped electrodes to generate periodic electrical field distribution and locally control the directors of uniformly aligned LCs. 5,6 The other is to directly guide the initial LC directors to realize periodic refractive index profile through patterned alignment layers [7][8][9] or holographic recording in polymer dispersed liquid crystals. 10,11 Linearly polarized light is needed for LC components which limits the optical efficiency, thus, introduction of approaches for polarization independent design is considerably important.…”

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confidence: 99%

Polarization independent liquid crystal gratings based on orthogonal photoalignments

Srivastava

Lin

et al. 2012

Appl. Phys. Lett.

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confidence: 99%

Polarization independent liquid crystal gratings based on orthogonal photoalignments

Srivastava

Lin

et al. 2012

Appl. Phys. Lett.

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“…To achieve such a distribution, various methods have been proposed. First, a special electrode configuration, such as interdigitated (or in-plane-switch, IPS) electrodes, is designed to produce a non-uniform electric field for fabricating the LC phase grating [6][7][8][9][10][11][12]. Other ways of generating the periodicity of the refractive index are through the reorientation of the LC molecular director using photoalignment [13,14], and the holographic technique [15,16].…”

Section: Introductionmentioning

confidence: 99%

Switchable Two-Dimensional Liquid Crystal Grating in Blue Phase

Huang

Lin

et al. 2017

Crystals

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Abstract:We demonstrate a switchable two-dimensional phase grating in blue phase liquid crystal (BPLC), which is fabricated by sawtooth in-plane-switch (IPS) electrodes. They are used to generate the horizontal electric field on a single indium-tin-oxide (ITO) glass substrate and, as a result, the 1-D and 2-D phase gratings can be mutual switched via different polarizations of incident light with an applied voltage. The first-order diffraction efficiency is up to 20% and 10% for the 1-D and 2-D phase grating at V = 150 V, respectively. Moreover, the rise and decay time is 0.9 and 1.1 ms, respectively, which is suitable for wide applications of high-speed optical manipulations.

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“…The most common approach deals with arrays of parallel electrodes for generating a longitudinal [5,6] or lateral [7,8] periodic electrical field distribution and locally controlling the directors of the LCs and thus the diffraction. The second strategy is to directly pattern the LC alignment layers either by microrubbing [9,10] or by patterned photoalignment [11] and guiding the LC director in different alignment domains.…”

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confidence: 99%

Optically tunable and rewritable diffraction grating with photoaligned liquid crystals

et al. 2013

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An optically tunable and rewritable liquid crystal (LC) diffraction grating cell has been revealed that consists of an optically active and an optically passive alignment layer. The grating profile is created by confining the LC director distribution in alternate planar and twisted alignment domains by means of photoalignment of the LCs. The proposed grating is optically tunable for diffractive and nondiffractive states with a small response time that depends on the exposure energy and LC parameters. In addition, the grating can be erased and rewritten for different diffracting characteristics. Another approach is to utilize the natural diffracting ability of the chiral LCs [12]. Such gratings are electrically tunable but cannot be tuned optically [12,13]. In recent years some reports dealing with optical tunability of dye-doped organic materials have been written [14]. Confined complex structures such as polymer-LC-polymer-slide (PLCPS) gratings containing azo compounds show optical switching times of 0.5 s at the irradiance of 245 mW∕cm 2 and diffraction efficiencies (DEs) up to 85% [15]. In another report, a 90% DE and switching time of 0.2 s (at the irradiance of 54 mW∕ cm 2 ) were reported for PLCPS with photosensitive LC [16]. Most of these reports include dye-doped LC for a photopolymerizable mixture for recording the grating. However, azo dyes, because of their chemical instability, are not stable in the LC mixture, and therefore the efficiency of these devices is highly limited and they manifest a rather complex fabrication procedure [17]. Another approach, based on a polydimethylsiloxane periodic microstructure on a glass substrate, separated by a thin LC film, with a DE of 35% and switching time of 145 s at the irradiance of 600 mW∕cm 2 , has been reported [18]. Other than LC, a metamaterial [19] fabricated by encapsulating photochromic solution in nano-holes of polycarbonate has also been proposed for fabricating optically tunable gratings [4]. The interference pattern by the green laser was used to write the grating profile, whereas it can be erases by UV irradiation [20,21]. However, the technology is restricted by the large switching time of ∼30 s (at an irradiance of 300 mW∕cm 2 ). Recently, we have disclosed a relatively easier and more reliable method to fabricate electrically tunable gratings, by defining the LC director in alternate alignment domains of alternate planar (PA) and twisted (TN) alignments by means of photoalignment [22]. Moreover, among all of these strategies, patterned photoalignment has been demonstrated to be efficient [11][12][13].In this article, we present an optically tunable LC grating based on PA and TN alignment domains. The blue light (λ 450 nm) can be used to tune the diffractive and nondiffractive states. Such gratings can also be erased and rewritten for different grating vectors. Thus, they could find several applications.The optically tunable and rewritable (OTRW) LC cell consists of two substrates with different aligning materials, one of which is optically pas...

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Fringing-field minimization in liquid-crystal-based high-resolution switchable gratings

Cited by 35 publications

References 10 publications

Polarization independent liquid crystal gratings based on orthogonal photoalignments

Polarization independent liquid crystal gratings based on orthogonal photoalignments

Switchable Two-Dimensional Liquid Crystal Grating in Blue Phase

Optically tunable and rewritable diffraction grating with photoaligned liquid crystals

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