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Lin T, Xie J, Zhou Y, Zhou Y, Yuan Y, Fan F, Wen S. Recent Advances in Photoalignment Liquid Crystal Polarization Gratings and Their Applications. Crystals 2021; 11:900. [DOI: 10.3390/cryst11080900] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Liquid crystal (LC) circular polarization gratings (PGs), also known as Pancharatnam–Berry (PB) phase deflectors, are diffractive waveplates with linearly changed optical anisotropy axes. Due to the high diffraction efficiency, polarization selectivity character, and simple fabrication process, photoalignment LC PGs have been widely studied and developed especially in polarization management and beam split. In this review paper, we analyze the physical principles, show the exposure methods and fabrication process, and present relevant promising applications in photonics and imaging optics.
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Chen P, Wei BY, Hu W, Lu YQ. Liquid-Crystal-Mediated Geometric Phase: From Transmissive to Broadband Reflective Planar Optics. Adv Mater 2020; 32:e1903665. [PMID: 31566267 DOI: 10.1002/adma.201903665] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/07/2019] [Indexed: 06/10/2023]
Abstract
Planar optical elements that can manipulate the multidimensional physical parameters of light efficiently and compactly are highly sought after in modern optics and nanophotonics. In recent years, the geometric phase, induced by the photonic spin-orbit interaction, has attracted extensive attention for planar optics due to its powerful beam shaping capability. The geometric phase can usually be generated via inhomogeneous anisotropic materials, among which liquid crystals (LCs) have been a focus. Their pronounced optical properties and controllable and stimuli-responsive self-assembly behavior introduce new possibilities for LCs beyond traditional panel displays. Recent advances in LC-mediated geometric phase planar optics are briefly reviewed. First, several recently developed photopatterning techniques are presented, enabling the accurate fabrication of complicated LC microstructures. Subsequently, nematic LC-based transmissive planar optical elements and chiral LC-based broadband reflective elements are reviewed systematically. Versatile functionalities are revealed, from conventional beam steering and focusing, to advanced structuring. Combining the geometric phase with structured LC materials offers a satisfactory platform for planar optics with desired functionalities and drastically extends exceptional applications of ordered soft matter. Some prospects on this rapidly advancing field are also provided.
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Affiliation(s)
- Peng Chen
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - Bing-Yan Wei
- MOE Key Laboratory of Material Physics and Chemistry under Extraordinary Conditions, and Shaanxi Key Laboratory of Optical Information Technology, School of Science, Northwestern Polytechnical University, Xi'an, 710072, China
| | - Wei Hu
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
- Institute for Smart Liquid Crystals, JITRI, Changshu, 215500, China
| | - Yan-Qing Lu
- National Laboratory of Solid State Microstructures, Key Laboratory of Intelligent Optical Sensing and Manipulation, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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Lin T, Zhou Y, Yuan Y, Fu W, Yao L, Huang H, Fan F, Wen S. Transflective spin-orbital angular momentum conversion device by three-dimensional multilayer liquid crystalline materials. Opt Express 2018; 26:29244-29252. [PMID: 30470090 DOI: 10.1364/oe.26.029244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 10/07/2018] [Indexed: 06/09/2023]
Abstract
In this paper, a liquid crystal device for generating transflected optical vortices with high efficiency based on Pancharatnam-Berry phase is devised and demonstrated experimentally. In the experiment, both photo-alignment material and polymer-alignment material are used for assembling three-dimensional distributed liquid crystal polymer and cholesteric liquid crystal. Through the interaction between the incident light and the device, both transmitted light and reflected light get spin-orbital angular momentum conversion. Moreover, the amount of transmitted and reflected beams can be modulated by the input polarization. In our proposal, the device is dual functional, low-cost and simple in manufacturing process.
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Nys I, Nersesyan V, Beeckman J, Neyts K. Complex liquid crystal superstructures induced by periodic photo-alignment at top and bottom substrates. Soft Matter 2018; 14:6892-6902. [PMID: 30091777 DOI: 10.1039/c8sm01145a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The formation of nematic liquid crystal (LC) superstructures in cells with non-uniform photo-alignment at the confining substrates is studied experimentally and by simulations. An interference pattern of left- and right-handed circularly polarized light is used to define the alignment at both substrates separately, so that the alignment varies along the x-coordinate on one substrate and along the y-coordinate on the other substrate. The interplay between the complex surface alignment and the liquid crystalline soft matter leads to the formation of interesting 3D configurations. The periodic LC structures that are formed in the bulk of the cell are analyzed experimentally by polarizing optical microscopy (POM) for different applied voltages. In the region with strong photo-alignment at both substrates, a 2D LC polarization grating (PG) with a complex 3D director configuration is formed. Distinct periodic structures with different symmetry properties are observed in the regions with weak illumination at the top and/or bottom substrate. The director configuration in the different regions was successfully simulated with the help of finite element (FE) Q-tensor simulations. The agreement between the simulations and the experiments was verified by comparing the POM images with simulated results for the transmission between crossed polarizers.
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Affiliation(s)
- Inge Nys
- Electronics and Information Systems Department, Ghent University, Technologiepark Zwijnaarde 15, 9052 Ghent, Belgium.
| | - Varsenik Nersesyan
- Electronics and Information Systems Department, Ghent University, Technologiepark Zwijnaarde 15, 9052 Ghent, Belgium. and Photonics Department, Institute for Physical Research of NAS RA, 0203 Ashtarak, Armenia
| | - Jeroen Beeckman
- Electronics and Information Systems Department, Ghent University, Technologiepark Zwijnaarde 15, 9052 Ghent, Belgium.
| | - Kristiaan Neyts
- Electronics and Information Systems Department, Ghent University, Technologiepark Zwijnaarde 15, 9052 Ghent, Belgium.
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Tang MJ, Chen P, Zhang WL, Tam AMW, Chigrinov VG, Hu W, Lu YQ. Integrated and reconfigurable optical paths based on stacking optical functional films. Opt Express 2016; 24:25510-25514. [PMID: 27828489 DOI: 10.1364/oe.24.025510] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
A strategy for integrated and reconfigurable optical paths based on stacking optical functional films is proposed. It is demonstrated by stacking two liquid crystal polymer q-plates and one quarter-wave plate for vector vortex beams generation. The topological charge and polarization order of generated vector vortex beams can be controlled independently by stacking and reordering different optical films with repeated adhesive ability. It supplies a low-cost, light-weight and versatile technique for reducing the volume of free-space optical system and has a great potential in optical researches and applications.
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Kawai K, Sakamoto M, Noda K, Sasaki T, Kawatsuki N, Ono H. Design and fabrication of a tunable wavelength-selective polarization grating. Appl Opt 2016; 55:6269-6274. [PMID: 27534469 DOI: 10.1364/ao.55.006269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Tunable wavelength-selective diffraction with polarization conversion is realized by the design of a liquid crystal (LC) grating containing a twisted nematic alignment structure that is fabricated by an efficient one-step photoalignment method. The diffraction efficiency strongly depends on the wavelength of the incident beam, and this property can be controlled by adjusting the birefringence of the nematic LC using a thermal control. These properties are well described by a theoretical analysis based on the Jones calculus and are experimentally demonstrated using 488, 532, and 633 nm wavelength incident polarized laser beams. The resultant LC grating has potential applications as diffractive optical elements that can simultaneously control the parameters of light such as amplitude, wavelength, and polarization.
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Ji Z, Zhang X, Shi B, Li W, Luo W, Drevensek-Olenik I, Wu Q, Xu J. Compartmentalized liquid crystal alignment induced by sparse polymer ribbons with surface relief gratings. Opt Lett 2016; 41:336-339. [PMID: 26766708 DOI: 10.1364/ol.41.000336] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We report on the liquid crystal (LC) alignment induced by sparse polymer ribbons fabricated by the two-photon polymerization-based direct laser writing method. Each ribbon is fabricated by a single scan of the laser through the photoresist and possesses surface relief gratings on both sides. The relief gratings are caused by the optical interference between the incident and reflected laser beams. With the aid of these relief gratings, LC molecules can be well aligned along the selected direction of the ribbons. LC cells with the Z-shaped and checkerboard-type microstructures are constructed based on the sparse out-of-plane polymeric ribbons. Our results show that with such polymer ribbons a compartmentalized LC alignment in the arbitrary microstructures can be realized.
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Nys I, Beeckman J, Neyts K. Switchable 3D liquid crystal grating generated by periodic photo-alignment on both substrates. Soft Matter 2015; 11:7802-7808. [PMID: 26313442 DOI: 10.1039/c5sm01294e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A planar liquid crystal (LC) cell is developed in which two photo-alignment layers have been illuminated with respectively a horizontal and a vertical diffraction pattern of interfering left- and right-handed circularly polarized light. In the bulk of the cell, a complex LC configuration is obtained with periodicity in two dimensions. Remarkably, the period of the structure is larger than the period of the interference pattern, indicating that lowering of the symmetry allows a reduction in the elastic energy. The liquid crystal configuration depends on the periodicity of the alignment but also on the thickness of the cell. By applying a voltage over the electrodes, the power going into the different diffracted orders can be tuned. Finite element (FE) simulations based on Q-tensor theory are used to find the 3D equilibrium director distribution, which is used to simulate the near-field transmission profile based on the Jones calculus. A 2D Fourier transform is performed for both the x- and y-component of the transmitted wave to find the diffraction efficiency.
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Affiliation(s)
- I Nys
- Liquid Crystals & Photonics Group, Department of Electronics and Information Systems, Ghent University, Sint-Pietersnieuwstraat 41, B-9000 Ghent, Belgium.
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