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He X, Zhang Z, Zhou F, Hu Y, Zou C, Gao Y, Wang Q, Yu M, Yang H. Study on the Effect of α-Substituted Acrylate Monomers on the Electro-Optical Properties of Polymer-Dispersed Liquid Crystal Films. ACS APPLIED MATERIALS & INTERFACES 2023; 15:58861-58872. [PMID: 38059631 DOI: 10.1021/acsami.3c13382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/08/2023]
Abstract
Polymer-dispersed liquid crystals (PDLCs) show great application potential in the areas of displays and smart windows. However, their electro-optical (E-O) properties such as contrast ratio and threshold voltage still need further improvement. In this study, the effects of α-substituted acrylate monomers on the morphology and E-O properties of PDLC composite films were systematically studied. It was found that the large substituent tended to increase the void size of the polymer matrix, while the small fluorine substitution led to a microsphere-type polymer morphology, which deteriorated the E-O performance. Finally, a largely improved E-O performance of low threshold voltage (0.437 V/μm), low saturation voltage (1.012 V/μm), and high contrast ratio (27) was achieved in an 8 μm-thick film by the addition of a chlorine-substituted monomer. This study provides a new approach for optimizing PDLCs from a material perspective.
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Affiliation(s)
- Xian He
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
| | - Zuowei Zhang
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
| | - Foxin Zhou
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
| | - Yongchuan Hu
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
| | - Cheng Zou
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
| | - Yanzi Gao
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
| | - Qian Wang
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
| | - Meina Yu
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
| | - Huai Yang
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
- Beijing Advanced Innovation Center for Materials Genome Engineering, University of Science and Technology Beijing, No. 30 Xueyuan Road, Haidian District, Beijing 100083, P. R. China
- School of Materials Science and Engineering, Peking University, No. 5 Yiheyuan Road, Haidian District, Beijing 100871, P. R. China
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Yu P, Chen X, Zhang D, Gao J, Ma C, Zhang C, He Z, Wang D, Miao Z. Polymer-Dispersed Liquid Crystal Films on Flexible Substrates with Excellent Bending Resistance and Spacing Stability. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:610-618. [PMID: 36541927 DOI: 10.1021/acs.langmuir.2c02895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Polymer-dispersed liquid crystals (PDLCs) are very attractive due to their electrically switchable properties. However, current PDLC films still have problems such as high driving voltages, low contrast ratio (CR), and poor bending resistance and spacing stability. To solve these problems, a PDLC film with a system of coexisting polymer spacer columns and polymer network was proposed. First, based on the adhesive systems of IBMA and UV6301, the effects of IBMA concentration and LC content on the morphology of the polymer network and the electro-optical properties of PDLC were investigated, respectively. Then, the effects of the process conditions of mask polymerization such as temperature, time, and UV light intensity on the morphology and electro-optical properties of the polymer spacer columns were systematically investigated. It was found that PDLC films with the coexistence system exhibit both excellent electro-optical properties and outstanding bending resistance and spacing stability. Thus, it provides new practical possibilities for the preparation of high-performance PDLC films used in flexible devices.
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Affiliation(s)
- Ping Yu
- Xi'an Key Laboratory of Advanced Photo-electronics Materials and Energy Conversion Device, School of Electronic Information, Xijing University, Xi'an 710123, China
- State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China
| | - Xianliang Chen
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Dongxia Zhang
- Xi'an Key Laboratory of Advanced Photo-electronics Materials and Energy Conversion Device, School of Electronic Information, Xijing University, Xi'an 710123, China
| | - Jianjing Gao
- Xi'an Key Laboratory of Advanced Photo-electronics Materials and Energy Conversion Device, School of Electronic Information, Xijing University, Xi'an 710123, China
| | - Cheng Ma
- Xi'an Key Laboratory of Advanced Photo-electronics Materials and Energy Conversion Device, School of Electronic Information, Xijing University, Xi'an 710123, China
| | - Cuihong Zhang
- Xi'an Key Laboratory of Advanced Photo-electronics Materials and Energy Conversion Device, School of Electronic Information, Xijing University, Xi'an 710123, China
| | - Zemin He
- Xi'an Key Laboratory of Advanced Photo-electronics Materials and Energy Conversion Device, School of Electronic Information, Xijing University, Xi'an 710123, China
| | - Dong Wang
- School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
| | - Zongcheng Miao
- School of Artificial Intelligence, Optics and Electronics (IOPEN), Northwestern Polytechnical University, Xi'an, Shaanxi 710072, China
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Huang CY, Lin SH. Polarization-Dependent Gratings Based on Polymer-Dispersed Liquid Crystal Cells with In-Plane Switching Electrodes. Polymers (Basel) 2022; 14:polym14020297. [PMID: 35054701 PMCID: PMC8779636 DOI: 10.3390/polym14020297] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/08/2022] [Accepted: 01/10/2022] [Indexed: 01/27/2023] Open
Abstract
A diffraction grating of polymer-dispersed liquid crystal (PDLC) with polarization-selective characteristics is investigated. Electrically controllable gratings are produced using In-Plane Switching (IPS) electrodes. Indium tin oxide (ITO) electrodes with a stripe pattern are used to generate a horizontal electric field parallel to the substrate on a single glass substrate. It is known from the experimental results that the number of diffraction orders can be controlled by applied voltage. Except for the zeroth order, the consistently highest intensity can be obtained for every other order of diffraction, and the polarization direction of the diffraction is perpendicular to the direction of the electrode stripes. The polarization direction of the zeroth order diffraction is parallel to the direction of the electrode stripes. Therefore, it can be used as a filter for light polarization.
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Affiliation(s)
- Chia-Yi Huang
- Department of Applied Physics, Tunghai University, Taichung 40704, Taiwan;
| | - Shih-Hung Lin
- Department of Optometry, Chung Shan Medical University, Taichung 40201, Taiwan
- Department of Ophthalmology, Chung Shan Medical University Hospital, Taichung 40201, Taiwan
- Correspondence:
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Huang CY, Lin SH. Organic Solvent Sensors Using Polymer-Dispersed Liquid Crystal Films with a Pillar Pattern. Polymers (Basel) 2021; 13:polym13172906. [PMID: 34502946 PMCID: PMC8434618 DOI: 10.3390/polym13172906] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 11/16/2022] Open
Abstract
An organic solvent sensor of polymer-dispersed liquid crystals (PDLCs) film is fabricated by a combination of tri-functional monomers and LCs. When the patterned PDLC film comes into contact with the organic solvent, the organic solvent will penetrate into the film to induce the orientation of the liquid crystals, which will change from an ordered to a disordered state, which causes the PDLC film to scatter incident light. The experiment used acetone and ethanol as the organic solvents of interest. The results show that the patterned PDLC film has a stronger response to acetone than to ethanol. Based on the difference in the intensity of light scattering and the response time of the patterned PDLC film to different organic solvents, the results can be used to identify and recognize different types of organic solvents.
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Affiliation(s)
- Chia-Yi Huang
- Department of Applied Physics, Tunghai University, Taichung 40704, Taiwan;
| | - Shih-Hung Lin
- Department of Optometry, Chung Shan Medical University, Taichung 40201, Taiwan
- Department of Ophthalmology, Chung Shan Medical University Hospital, Taichung 40201, Taiwan
- Correspondence:
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Oh SW, Jeon BG, Choi TH, Do SM, Yoon TH. Independent control of haze and total transmittance with a dye-doped liquid crystal phase-grating device. APPLIED OPTICS 2019; 58:4315-4319. [PMID: 31251235 DOI: 10.1364/ao.58.004315] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 05/08/2019] [Indexed: 06/09/2023]
Abstract
This paper presents a dye-doped liquid crystal (LC) phase-grating cell that is switchable between transparent, dark, and opaque states. The device can control haze and transmittance independently. Initially, LC and dye molecules are twist-aligned to make the cell opaque but haze-free due to the absorption of incident light without scattering. Switching to the transparent state could be achieved by applying a vertical electric field, whereas switching to the opaque state could be achieved by applying an in-plane electric field. It exhibited several advantages, such as a low switching voltage (<18 V) and fast response time (<30 ms).
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Huh JW, Seo JH, Oh SW, Kim SH, Yoon TH. Tristate switching of a liquid-crystal cell among initial transparent, haze-free dark, and high-haze dark states. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.02.082] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Liang ZY, Tu CY, Yang TH, Liu CK, Cheng KT. Low-Threshold-Voltage and Electrically Switchable Polarization-Selective Scattering Mode Liquid Crystal Light Shutters. Polymers (Basel) 2018; 10:E1354. [PMID: 30961278 PMCID: PMC6401727 DOI: 10.3390/polym10121354] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 11/16/2018] [Accepted: 11/30/2018] [Indexed: 11/16/2022] Open
Abstract
Low-threshold-voltage (Vth) and electrically switchable, polarization-selective scattering mode light shutters (PSMLSs) using polymer-dispersed liquid crystals (PDLCs) are demonstrated in this work. The optimized weight ratio of the nematic liquid crystals (LCs) to the adopted monomer (NBA107, Norland Optics) in the low-Vth PDLCs based on NBA107 is 7:3, [7:3]-PDLCsNBA107. The properties of the low-Vth PDLCsNBA107, such as light-scattering performance, initial transmission, Vth, and droplet size were investigated. Experiment results show that the surface anchoring (threshold-voltage) of NBA107 is weaker (lower) than or equal to that of the common NOA65. The cost is that the response time of the proposed PDLCsNBA107 is relatively long. A method to reduce the decay time, which can be applied to all other PDLC devices, will be elucidated. In addition to the low Vth of the proposed PDLCsNBA107, the operation voltage (~6 Vrms) to approach the maximum transmission is relatively low in a 7 μm-thick PDLCsNBA107 cell. Moreover, the polarization-selective light-scattering performances of the proposed PSMLSs based on the [7:3]-PDLCsNBA107, mainly driven by in-plane and vertical fields, are also demonstrated.
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Affiliation(s)
- Zhe-Yung Liang
- Department of Optics and Photonics, National Central University, 320 Taoyuan, Taiwan.
| | - Ching-Yen Tu
- Department of Optics and Photonics, National Central University, 320 Taoyuan, Taiwan.
| | - Tsung-Hsun Yang
- Department of Optics and Photonics, National Central University, 320 Taoyuan, Taiwan.
| | - Cheng-Kai Liu
- Department of Optics and Photonics, National Central University, 320 Taoyuan, Taiwan.
| | - Ko-Ting Cheng
- Department of Optics and Photonics, National Central University, 320 Taoyuan, Taiwan.
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Meng C, Tseng M, Tang S, Kwok H. Optical rewritable liquid crystal displays without a front polarizer. OPTICS LETTERS 2018; 43:899-902. [PMID: 29444022 DOI: 10.1364/ol.43.000899] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 01/18/2018] [Indexed: 06/08/2023]
Abstract
A front polarizer-free optically rewritable (ORW) liquid crystal display (LCD) has been made via a hybrid alignment configuration with dye-doped LCs. The hybrid structure consists of one optically active planar and one optically passive homeotropic alignment layer. The rewritability of the device is achieved by photo-reorienting the azo dye molecules in the active planar alignment layer. The dye is doped in LCs to function as a polarizer by following the LCs' direction via a guest-host effect so that the front polarizer can be eliminated. This makes the device more compact and easier to operate for image erasing and rewriting. The image rewriting time only requires ∼9.0 s, which is determined by the exposure energy and LC parameters. The hybrid-mode dye-doped ORW LCD devices could find applications in E-paper, transparent display, and various photonics devices.
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Chan CH, Wu TY, Yen MH, Lin CE, Cheng KT, Chen CC. Low power consumption and high-contrast light scattering based on polymer-dispersed liquid crystals doped with silver-coated polystyrene microspheres. OPTICS EXPRESS 2016; 24:29963-29971. [PMID: 28059381 DOI: 10.1364/oe.24.029963] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Polymer-dispersed liquid crystals (PDLCs) have attracted considerable attention for optical device applications in recent years. However, the high operating voltage of PDLCs limits their applications. This study reports a simple approach used for the first time to decrease the operating voltage of PDLCs by means of doping 3 μm-diameter silver-coated polystyrene microspheres (Ag-coated PSMSs) into PDLCs. Ag-coated PSMSs construct an induced electric field between each other when an external electric field is applied. This induced electric field can enhance the effective electric field so the operating voltage can be actively reduced from 77 V to 40 V. Such PDLCs also possess a high contrast ratio of >50 and a high on-state transmittance of ~73%. Therefore, PDLCs doped with Ag-coated PSMSs maintain a high contrast ratio and improve their electro-optical properties.
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Suresh J, Karthik S, Arun A. Cis-trans isomerism shown by the polymer containing chalcone moiety in its side chain. POLYM ADVAN TECHNOL 2016. [DOI: 10.1002/pat.3791] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- J. Suresh
- PG and Research Department of Chemistry, Government Arts College; Thiruvannamalai 606603 Tamilnadu India
| | - S. Karthik
- PG and Research Department of Chemistry, Government Arts College; Thiruvannamalai 606603 Tamilnadu India
| | - A. Arun
- PG and Research Department of Chemistry, Government Arts College; Thiruvannamalai 606603 Tamilnadu India
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Liu YC, Cheng KT, Chen HF, Fuh AYG. Photo- and electro-isomerization of azobenzenes based on polymer-dispersed liquid crystals doped with azobenzenes and their applications. OPTICS EXPRESS 2014; 22:4404-4411. [PMID: 24663763 DOI: 10.1364/oe.22.004404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report the photo-isomerization and electro-isomerization effects in azobenzenes-doped polymer-dispersed liquid crystals during the switching of the liquid crystal (LC) device between transparent (cis-isomers dominant) and scattering states (trans-isomers dominant). The isothermal phase transition, which is a result of the illumination of UV light and the application of DC voltage, was the main mechanism to switch the LC device between transparency, scattering, and gray scales. This study discusses in detail the variations in the population of cis-isomers as functions of the period and the amplitude of the applied DC voltage.
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Yu BH, Huh JW, Kim KH, Yoon TH. Light shutter using dichroic-dye-doped long-pitch cholesteric liquid crystals. OPTICS EXPRESS 2013; 21:29332-7. [PMID: 24514486 DOI: 10.1364/oe.21.029332] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We propose a light shutter device using dichroic-dye-doped liquid crystals (LCs) whose Bragg reflection wavelength is set to be infrared by controlling the pitch of cholesteric liquid crystals (ChLCs). A dye-doped long-pitch ChLC cell is switchable between the dark planar state and the transparent homeotropic state. It has the advantages of high transmittance, low operation voltage, and an easy fabrication process relative to previous LC light shutter devices. The proposed light shutter device is expected to achieve high visibility for transparent organic light-emitting diode displays and emerging smart windows, which can be used in airplanes, cars, and other similar applications.
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Yaroshchuk O, Reznikov Y. Photoalignment of liquid crystals: basics and current trends. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c1jm13485j] [Citation(s) in RCA: 403] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Lee GH, Hwang KY, Jang JE, Jin YW, Lee SY, Jung JE. Bright color optical switching device by polymer network liquid crystal with a specular reflector. OPTICS EXPRESS 2011; 19:13097-13104. [PMID: 21747462 DOI: 10.1364/oe.19.013097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The color optical switching device by polymer network liquid crystal (PNLC) with color filter on a specular reflector shows excellent performance; white reflectance of 22%, color gamut of 32%, and contrast ratio up to 50:1 in reflective mode measurement. The view-angle dependence of the reflectance can be adjusted by changing the PNLC thickness. The color chromaticity shown by the device is close to the limit value of color filters, and its value nearly remains with respect to the operating voltage. These optical properties of the device can be explained from the prediction based on multiple interactions between the light and the droplets of liquid crystal. The high reflectance, vivid color image, and moderate responds time allow the PNLC device to drive good color moving image. It can widely extend the applications of the reflective device.
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Affiliation(s)
- Gae Hwang Lee
- Material and Device Research Center, Samsung Advanced Institute of Technology, Yongin-si, Gyeonggi-do, Korea
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Chen YD, Cheng KT, Liu CK, Fuh AYG. Polarization rotators fabricated by thermally-switched liquid crystal alignments based on rubbed poly(N-vinyl carbazole) films. OPTICS EXPRESS 2011; 19:7553-7558. [PMID: 21503063 DOI: 10.1364/oe.19.007553] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This paper demonstrates the thermally-switched liquid crystal (LC) alignments based on a rubbed poly(N-vinyl carbazole) (PVK) film, and their application for polarization rotators. The mechanically rubbed PVK layer can induce a planar alignment of LCs with their director axis perpendicular to the direction of rubbing. This direction can be switched toward the rubbing direction by thermal treatment. Experimentally, the angle of re-orientation of the director axis increases with the temperature in a specific range of temperatures. In this study, the optical properties of linear and concentric polarization rotators, fabricated using a rubbed PVK film with thermal treatment, are examined.
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Affiliation(s)
- Yuan-Di Chen
- Institute of Electro-optical Science and Engineering, National Cheng Kung University, Tainan 70101, Taiwan
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Fuh AYG, Chen CC, Cheng KT, Liu CK, Chen WK. Polarization-independent holographic gratings based on azo-dye-doped polymer-dispersed liquid-crystal films. APPLIED OPTICS 2010; 49:275-280. [PMID: 20062516 DOI: 10.1364/ao.49.000275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We demonstrate polarization-independent holographic gratings (PIHGs) based on azo-dye-doped polymer-dispersed liquid crystal films. The PIHGs are recorded by irradiation under an intensity-modulated interference field, generated by two linearly polarized green optical beams, and by simultaneously applying a suitable AC voltage to the sample. The photoexcited azo dyes are adsorbed onto the UV-cured polymer film with their long axes parallel to the normal of the substrate. When the applied voltage is switched off, the PIHGs are generated with periodic modulation of liquid-crystal structures with transparently homeotropic and randomly scattered alignments. Additionally, the generated PIHGs can be completely switched off by an applied voltage.
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Affiliation(s)
- Andy Ying-Guey Fuh
- Department of Physics, National Cheng Kung University, Tainan 701, Taiwan
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