Vladimir Chigrinov - Academia.edu (original) (raw)

Papers by Vladimir Chigrinov

IEEE/OSA Journal of Display Technology, Sep 1, 2005

Liquid crystal (LC) photo-alignment using azo-dyes is reviewed. This alignment method is very dif... more Liquid crystal (LC) photo-alignment using azo-dyes is reviewed. This alignment method is very different from previously reported ones, which are due to mechanisms such as photo-crosslinking, photo degradation, and photo-isomerization. We present the basic physical mechanisms of the photo-induced orientational order in various photo-aligning materials and in azo-dye layers in particular. This method is based on rotational diffusion in a potential created by the light field as well as intermolecular forces. It will be shown that this photo-aligning method can provide a controllable pretilt angle and strong anchoring energy of the LC cell, as well as having high thermal and ultraviolet (UV) stability. The application of this method to the alignment and fabrication of various types of LC displays is also discussed.

Crystals, Apr 20, 2020

We demonstrate a physical model of photoalignment and photopatterning based on rotational diffusi... more We demonstrate a physical model of photoalignment and photopatterning based on rotational diffusion in solid azo-dye nanolayers. We also highlight the new applications of photoalignment and photopatterning in display and photonics such as: (i) liquid crystal (LC) E-paper devices, including optically rewritable LC E-paper on flexible substrates as 3D E-paper, as well as optically rewritable technology for photonics devices; (ii) photonics LC devices, such as LC Switches, polarization controllers and polarization rotators, variable optical attenuators, LC filled photonic crystal fiber, switchable diffraction grating; (iii) patterned micro-polarizer array using photo-alignment technology for image sensor; (iv) electrically tunable liquid crystal q-plates; (v) electrically switchable liquid crystal Fresnel lens; (vi) liquid crystal optical elements with integrated Pancharatnam-Berry phases. We are sure, that in the field of (LC), the main point is no longer display research, but new photonic applications of LC are emerging in telecommunication, fiber optical communication systems, sensors, switchable lenses, LC light converters and other LC photonics devices.

Sid's Digest Of Technical Papers, 2003

Effect of photoaligning azo-dye layers thickness on the alignment quality and multiplex operation... more Effect of photoaligning azo-dye layers thickness on the alignment quality and multiplex operation of passively addressed ferroelectric liquid crystal (FLC) 1.5µm display cells has been investigated. An optimal (about 3~5 nm) azo-dye layer thickness, that provides both the highest multiplex operation steadiness and the best contrast ratio of FLC display cells was found.

Sid's Digest Of Technical Papers, May 1, 2007

Liquid crystal photo-alignment using azo-dyes for display and photonics applications is discussed... more Liquid crystal photo-alignment using azo-dyes for display and photonics applications is discussed. Various types of the glass and plastic substrates are used. Special types of 3D LC alignment, LC alignment inside thin micro tubes, and LC cladding layers in Si based waveguides and grating surface are concerned. The azo-dye photoalignment of polymerized LC films used as optical elements, such as polarizers and phase retarders is also considered. Optically rewritable liquid crystal display for plastic cards applications is shown.

Sid's Digest Of Technical Papers, Jun 1, 2011

If it is the author's pre-published version, changes introduced as a result of publishing process... more If it is the author's pre-published version, changes introduced as a result of publishing processes such as copy-editing and formatting may not be reflected in this document. For a definitive version of this work, please refer to the published version.

Sid's Digest Of Technical Papers, Jun 1, 2012

Crystals, Mar 6, 2017

In this article, a ferroelectric liquid crystal (FLC) dammann grating (DG) is demonstrated based ... more In this article, a ferroelectric liquid crystal (FLC) dammann grating (DG) is demonstrated based on the patterned photoalignment technology. By applying low electric field (10 V) on the FLC DG, the grating can switch between a diffractive state with 7 × 7 optical spots array and a non-diffractive state, depending on the polarity of electric field. The FLC DG shows very fast switching speed with switching on time and off time to be only 81 µs and 59 µs respectively. Comparing with other fast LC DGs such as the ones based on blue phase LC or dual-frequency LC, the switching speed of the proposed FLC DG is about one order faster, which provides great potential and perspective for the FLC DG to be applied in a broad range of optical applications such as optical communication and beam shaping.

Applied Optics, Mar 25, 2014

In this article, we disclose a method to fabricate a liquid crystal (LC) Fresnel zone lens (FZL) ... more In this article, we disclose a method to fabricate a liquid crystal (LC) Fresnel zone lens (FZL) with high efficiency. The LCFZL, based on patterned planar-aligned regions, has been prepared by means of a twostep photoalignment technique. The proposed binary-phase LCFZL manifests 39% diffraction efficiency at the focal point, which is close to the theoretical limit, 41%. Moreover, because of a lower driving voltage and faster response time, these elements could find application in many modern devices.

$Research paper thumbnail of Optically tunable and rewritable diffraction grating with photoaligned liquid crystals$

Optics Letters, Jun 27, 2013

An optically tunable and rewritable liquid crystal (LC) diffraction grating cell has been reveale... more 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. These optically tunable diffractive elements could find application in various photonic devices.

Applied Physics Letters, Jun 11, 2007

A method to generate any liquid crystal pretilt angle is proposed and demonstrated. This method i... more A method to generate any liquid crystal pretilt angle is proposed and demonstrated. This method is based on deep ultraviolet photoalignment of a layer consisting of nanostructured domains of horizontal and vertical alignment polyimides. Competition between the two types of domains produces the controlled pretilt angle. The obtained anchoring energy is reasonably large.

Physical review, Dec 15, 2003

The photoinduced alignment of a liquid crystal ͑LC͒ on films of azo dyes was studied for the liqu... more The photoinduced alignment of a liquid crystal ͑LC͒ on films of azo dyes was studied for the liquid crystal display applications. In order to improve the alignment stability of the photoaligned dye ͑SD-1͒, the azo-dye derivative with polymerizable terminal groups was synthesized ͑SDA-1͒. The films of SDA-1 exhibit good photoalignment properties and ultraviolet stability after thermal polymerization. We investigated the anchoring coefficient for polar and azimuthal energy for both azo-dyes SD-1 and SDA-1 using a differential method developed by us. The polar and azimuthal anchoring strengths of azo-dye aligning materials are comparable with those of usual polyimide aligning materials. The electro-optic response of a 90°twisted LC cell remains almost the same after heating up to 200 °C, i.e., the anchoring energy remains considerably high.

Polymers, Aug 21, 2017

As one of the diffractive optical elements, circular Dammann grating has shown its excellent vers... more As one of the diffractive optical elements, circular Dammann grating has shown its excellent versatility in practical applications. The electrically switchable Dammann grating has been extensively investigated; however, the research on the optically tunable circular Dammann grating has received less attention and reports on this subject have been insufficient in the past decade. In this paper, three-order and eight-order binary-phase liquid crystal circular Dammann gratings with two mutually orthogonal photo-induced alignments in every two adjacent alignment domains, fabricated by a micro-patterned liquid crystal polymer phase mask, are proposed to generate annular uniform-intensity patterns in the far field. A simple maskless optical tuning of an eight-order liquid crystal circular Dammann grating is demonstrated by controlling the polarization of an ultraviolet light as well as the energy dose. The proposed liquid crystal circular Dammann gratings with high efficiencies and desirable uniformities exhibit outstanding optical as well as electrical tunabilities, enabling the widespread prospective applications in adaptive photonic chips stimulated flexibly by only light or by the combination of light and electric field.

Crystals, 2022

We report a ferroelectric liquid crystal (FLC) compound lens based on the Pancharatnam–Berry (PB)... more We report a ferroelectric liquid crystal (FLC) compound lens based on the Pancharatnam–Berry (PB) phase. The phase of the FLC compound lens is an integration of polarization grating and a PB lens. Thus, when light passes through an FLC compound lens, the output light’s polarization handedness will be changed accordingly. In this case, FLC compound lenses can function as concave/convex lenses with spatially separated output light and rapid transmittance tunability. The FLC compound lenses were fabricated using a single-step holographic exposure system, based on a spatial light modulator working as numerous phase retarders. Photosensitive azo-dye material was used as the aligning layer. The output light transmittance of the FLC compound lens can be operated at 150 μs. Our results achieve the potential applications on various displays and augmented reality.

Optics express, Jan 19, 2018

A two-dimensional (2D) pure polarization pattern via four-beam polarization interferometry of cir... more A two-dimensional (2D) pure polarization pattern via four-beam polarization interferometry of circularly polarized beams is demonstrated both theoretically and experimentally. The polarization orientation of the interference pattern is recorded by an azobenzene photoalignment layer and transferred to liquid crystal (LC), enabling the fabrication of a 2D liquid crystal (LC) chiral structure. This structure behaves as a 2D LC polarization grating (LCPG) that can generate multiple polarization-selective diffraction beams of orthogonal polarization states with high efficiency. This 2D LCPG provides an effective way to distribute an optical signal into multiple receivers by both incidence polarization control and external electric field, therefore offering potential applications on multi-channel optical communication and information processing.

Liquid Crystals and their Application, 2016

Basic electro-optical effects in ferroelectric liquid crystals are considered in terms of their p... more Basic electro-optical effects in ferroelectric liquid crystals are considered in terms of their physical nature and potential applications in display and photonic devices of a new generation.

Polymers, 2017

Photoalignment of Liquid Crystalline Materials, 2008

Photoalignment possesses significant advantages in comparison with the usual 'rubbing' treatment ... more Photoalignment possesses significant advantages in comparison with the usual 'rubbing' treatment of the substrates of liquid crystal display (LCD) cells as it is a non-contact method with a high resolution. A new technique recently pioneered by the authors of this book, namely the photo-induced diffusion reorientation of azodyes, does not involve any photochemical or structural transformations of the molecules. This results in photoaligning films which are robust and possess good aligning properties making them particularly suitable for the new generation of liquid crystal devices. Photoalignment of Liquid Crystalline Materials covers state-of-the-art techniques and key applications, as well as the authors' own diffusion model for photoalignment. The book aims to stimulate new research and development in the field of liquid crystalline photoalignment and in so doing, enable the technology to be used in large scale LCD production. • Provides a full examination of the mechanisms of photoalignment. • Examines the properties of liquid crystals during photoalignment, with particular reference made to the effect on their chemical structure and stability. • Considers the most useful photosensitive materials and preparation procedures suitable for liquid crystalline photoalignment. • Presents several methods for photoalignment of liquid crystals. • Compares various applications of photoalignment technology for in-cell patterned polarizers and phase retarders, transflective and micro displays, security and other liquid crystal devices. Through its interdisciplinary approach, this book is aimed at a wide range of practising electrical engineers, optical engineers, display technologists, materials scientists, physicists and chemists working on the development of liquid crystal devices. It will also appeal to researchers and graduate students taking courses on liquid crystals or display technologies. The Society for Information Display (SID) is an international society, which has the aim of encouraging the development of all aspects of the field of information display. Complementary to the aims of the society, the Wiley-SID series is intended to explain the latest developments in information display technology at a professional level. The broad scope of the series addresses all facets of information displays from technical aspects through systems and prototypes to standards and ergonomics Vladimir G. Chigrinov obtained his PhD degree in solid-state physics from the Shubnikov Institute of Crystallography, USSR Academy of Sciences, in 1978. In 1988, he defended his doctoral degree and became a professor at the Shubnikov Institute of Crystallography, where he was a leading researcher from 1996. He joined HKUST in 1999 and is currently an associate professor. Since 1974 Professor Chigrinov has published 2 books. 15 reviews and book chapters, about 150 journal papers, more than 300 conference presentations, and holds more than 50 patents and patent applications in the field of liquid crystals. He is a Senior SID Member, SID Fellow and an Associate Editor of the Journal of the Society for Information Display. Vladimir M. Kozenkov graduated from the Moscow Energetic Institute as a scientist in applied physical optics (laser department). For 30 years he worked at the Organic Intermediates and Dyes Institute (NIOPIK) in Moscow. He pioneered research and development of various organic photosensitive materials for holography, waveguide, integral and polarization optics, stereolithography, optical memory, imaging processing, and security applications. He was the first to discover the phenomenon of photoinduced birefringence in polyvinyl-cinnamate films in 1977. He has published more than 100 refereed papers and holds more than 50 patents. Hoi-Sing Kwok obtained his PhD degree in applied physics from Harvard University in 1978. He joined the State University of New York at Buffalo in 1980 and became a full professor in 1985. He joined HKUST in 1992 an is currently Director of the Center for Display Research ( www.cdr.ust.hk). Professor Kwok has written over 500 refereed publications and holds 40 patents in laser optics and LCD technologies. He is a Fellow of the OSA, the IEEE, and the SID.

Emerging Liquid Crystal Technologies X, 2015

A polarized liquid crystal (LC) lens composed of a LC layers as a polarization switch and a liqui... more A polarized liquid crystal (LC) lens composed of a LC layers as a polarization switch and a liquid crystal and polymer composites lens (LCPC lens) is demonstrated with electrically switching (ES) mode and optically rewritten (ORW) mode. The lens power of LCPC lens is related to a polarization state of light modulated by the LC layer whose orientations are manipulated either electrically or optically. As a result, the LC lens is not only electrically switchable, but also optically rewritable. Each mode, ES mode or ORW mode, exhibits two discrete lens powers (-1.39 Diopter and +0.7 Diopter). The demonstrated aperture size is 10 mm. The detail optical mechanism is also discussed. The Modulation Transfer Function (so-called MTF) of the lens is measured as well. In addition, the image performance and the dispersion of the LC lens are investigated. Such a polarized LC lens could be a special switch in optical systems due to dual operation modes.

The photo-induced alignment quality of a ferroelectric liquid crystas (FLC) onto a photochemical ... more The photo-induced alignment quality of a ferroelectric liquid crystas (FLC) onto a photochemical stable azodye film was studied for various procedures of the azodye film photo -treatment and the FLC structure. The alignment quality of FLC depends mainly on the order para meter of the azodye film, however the structure of FLC layer is also important. So, the photo-aligned deformed helix ferroelectric (DHF) liquid crystal exhibits the contrast ratio CR>500:1, while for the helix free FLC the contrast ratio CR>1500:1.

$Research paper thumbnail of Optically tunable and rewritable diffraction grating with photoaligned liquid crystals$