Pub Date : 2016-07-02DOI: 10.1080/21680396.2016.1233079
Pengcheng Zhou, Yan Li, Xiao Li, Shuxin Liu, Yikai Su
ABSTRACT Liquid crystals (LCs) are widely used in nonlinear optics because of their sensitive responses to optical stimulation. Combined with other optoelectronic materials such as azo dyes, quantum dots (QDs), etc., LCs show very large optical nonlinearity which makes them suitable for applications in optical information processing, including holographic display and holographic storage. In this review, we present an overview of recent efforts on holographic display and storage based on liquid crystalline materials. Emphasis is placed on the dynamic holographic display which uses fast-response LCs doped with azo dye and QD. In this application, we discuss how to improve the response speed, resolution, and diffraction efficiency of liquid crystalline materials to realize high frame rate, large-size and high-brightness holographic displays. Some LC materials for holographic storage are also introduced, including polymer-dispersed liquid crystals, blue-phase liquid crystals, and azobenzene polymer liquid crystals, which have permanent response to light stimulation. The mechanisms of optical nonlinearities are discussed in detail, as a foundation for the physical process of LC-based holographic display and storage.
{"title":"Holographic display and storage based on photo-responsive liquid crystals","authors":"Pengcheng Zhou, Yan Li, Xiao Li, Shuxin Liu, Yikai Su","doi":"10.1080/21680396.2016.1233079","DOIUrl":"https://doi.org/10.1080/21680396.2016.1233079","url":null,"abstract":"ABSTRACT Liquid crystals (LCs) are widely used in nonlinear optics because of their sensitive responses to optical stimulation. Combined with other optoelectronic materials such as azo dyes, quantum dots (QDs), etc., LCs show very large optical nonlinearity which makes them suitable for applications in optical information processing, including holographic display and holographic storage. In this review, we present an overview of recent efforts on holographic display and storage based on liquid crystalline materials. Emphasis is placed on the dynamic holographic display which uses fast-response LCs doped with azo dye and QD. In this application, we discuss how to improve the response speed, resolution, and diffraction efficiency of liquid crystalline materials to realize high frame rate, large-size and high-brightness holographic displays. Some LC materials for holographic storage are also introduced, including polymer-dispersed liquid crystals, blue-phase liquid crystals, and azobenzene polymer liquid crystals, which have permanent response to light stimulation. The mechanisms of optical nonlinearities are discussed in detail, as a foundation for the physical process of LC-based holographic display and storage.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":"6 1","pages":"100 - 83"},"PeriodicalIF":5.1,"publicationDate":"2016-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2016.1233079","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60431146","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-07-02DOI: 10.1080/21680396.2016.1271367
P. Kahl, L. Noirez
ABSTRACT Recent experimental developments show that without reticulation links or entanglements, the isotropic phase of liquid crystals can work mechanically as an elastomer and optically as a harmonic oscillator at the sub-millimetre scale. The strength of the elastic response depends on the molecular architecture and is enhanced when the liquid-crystal molecules are attached as side-chain moieties to a chain backbone. This elastomeric behaviour of the isotropic phase is evidenced via stress and optical responses to a low-frequency mechanical excitation. Visible far away from any phase transition, this spectacular effect contains important information: the liquid state is a low threshold elastic medium; molecules are dynamically correlated and this elastic correlation is observed up to the sub-millimetre scale. This discovery sheds a new light on the origin of well-known effects as flow birefringence, shear banding in complex fluids or flow instabilities in simple liquids. The present paper emphasizes the key role of long range elastic interactions for a comprehensive approach to the flow birefringence, from its origins and to new possible applications.
{"title":"From flow birefringence in the isotropic phase of liquid crystals to the identification of shear elasticity in liquids","authors":"P. Kahl, L. Noirez","doi":"10.1080/21680396.2016.1271367","DOIUrl":"https://doi.org/10.1080/21680396.2016.1271367","url":null,"abstract":"ABSTRACT Recent experimental developments show that without reticulation links or entanglements, the isotropic phase of liquid crystals can work mechanically as an elastomer and optically as a harmonic oscillator at the sub-millimetre scale. The strength of the elastic response depends on the molecular architecture and is enhanced when the liquid-crystal molecules are attached as side-chain moieties to a chain backbone. This elastomeric behaviour of the isotropic phase is evidenced via stress and optical responses to a low-frequency mechanical excitation. Visible far away from any phase transition, this spectacular effect contains important information: the liquid state is a low threshold elastic medium; molecules are dynamically correlated and this elastic correlation is observed up to the sub-millimetre scale. This discovery sheds a new light on the origin of well-known effects as flow birefringence, shear banding in complex fluids or flow instabilities in simple liquids. The present paper emphasizes the key role of long range elastic interactions for a comprehensive approach to the flow birefringence, from its origins and to new possible applications.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":"4 1","pages":"135 - 151"},"PeriodicalIF":5.1,"publicationDate":"2016-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2016.1271367","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60431161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-07-02DOI: 10.1080/21680396.2016.1244020
N. Éber, P. Salamon, A. Buka
ABSTRACT Electric field-induced patterns in liquid crystals have been observed and studied for about 50 years. During this time, a great variety of structures, detected under different conditions, have been described; theoretical descriptions were also developed parallel with the experiments and a huge number of papers have been published. The non-vanishing interest in the topic is due to several factors. First, most experimentalists working with new (or even well-known) liquid crystals apply sooner or later an electric field for different purposes and, as a response, often (maybe undesirably or unexpectedly) have to face with emergence of patterns. Second, understanding the complexity of the formation mechanism of regular patterns in a viscous, anisotropic fluid is an extremely challenging theoretical task. Third, specialists in display fabrication or in other applications are also interested in the results; either to make use of them or in order to avoid field-induced patterns. In this review, we attempt to provide a systematic overview of the large amount of published results, focusing on recent achievements, about the three main types of electric field-induced patterns: transient patterns during the Freedericksz transition, flexoelectric domains and electroconvection. As a result of different instability mechanisms, a variety of pattern morphologies may arise. We address the physical background of the mechanisms, specify the conditions under which they may become effective, discuss the characteristics of the patterns, and summarize the possibilities of morphological transitions induced by frequency, voltage or temperature variations. Special emphasis is given to certain topics, which recently have gained enhanced interest from experimental as well as theoretical point of view, like driving with ultra-low frequencies or non-sinusoidal (superposed) waveforms, and the dynamics of defects and embedded colloidal particles. Assisting newcomers to the field, we also mention some, yet unresolved, problems, which may need further experimental and/or theoretical studies.
{"title":"Electrically induced patterns in nematics and how to avoid them","authors":"N. Éber, P. Salamon, A. Buka","doi":"10.1080/21680396.2016.1244020","DOIUrl":"https://doi.org/10.1080/21680396.2016.1244020","url":null,"abstract":"ABSTRACT Electric field-induced patterns in liquid crystals have been observed and studied for about 50 years. During this time, a great variety of structures, detected under different conditions, have been described; theoretical descriptions were also developed parallel with the experiments and a huge number of papers have been published. The non-vanishing interest in the topic is due to several factors. First, most experimentalists working with new (or even well-known) liquid crystals apply sooner or later an electric field for different purposes and, as a response, often (maybe undesirably or unexpectedly) have to face with emergence of patterns. Second, understanding the complexity of the formation mechanism of regular patterns in a viscous, anisotropic fluid is an extremely challenging theoretical task. Third, specialists in display fabrication or in other applications are also interested in the results; either to make use of them or in order to avoid field-induced patterns. In this review, we attempt to provide a systematic overview of the large amount of published results, focusing on recent achievements, about the three main types of electric field-induced patterns: transient patterns during the Freedericksz transition, flexoelectric domains and electroconvection. As a result of different instability mechanisms, a variety of pattern morphologies may arise. We address the physical background of the mechanisms, specify the conditions under which they may become effective, discuss the characteristics of the patterns, and summarize the possibilities of morphological transitions induced by frequency, voltage or temperature variations. Special emphasis is given to certain topics, which recently have gained enhanced interest from experimental as well as theoretical point of view, like driving with ultra-low frequencies or non-sinusoidal (superposed) waveforms, and the dynamics of defects and embedded colloidal particles. Assisting newcomers to the field, we also mention some, yet unresolved, problems, which may need further experimental and/or theoretical studies.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":"4 1","pages":"101 - 134"},"PeriodicalIF":5.1,"publicationDate":"2016-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2016.1244020","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60431155","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-01-02DOI: 10.1080/21680396.2016.1193065
R. J. Hernández, C. Provenzano, A. Mazzulla, P. Pagliusi, M. Viola, G. Cipparrone
ABSTRACT This article reviews the main results from the investigations performed on solid chiral microparticles based on polymerized cholesteric droplets. The procedures of particles generation, the structural characterization, optomechanics and microphotonics investigations are shown. The aim of this work is to give a picture of the innovation introduced by exploring the combination of chirality, self-organization and solid structure.
{"title":"Cholesteric solid spherical microparticles: chiral optomechanics and microphotonics","authors":"R. J. Hernández, C. Provenzano, A. Mazzulla, P. Pagliusi, M. Viola, G. Cipparrone","doi":"10.1080/21680396.2016.1193065","DOIUrl":"https://doi.org/10.1080/21680396.2016.1193065","url":null,"abstract":"ABSTRACT This article reviews the main results from the investigations performed on solid chiral microparticles based on polymerized cholesteric droplets. The procedures of particles generation, the structural characterization, optomechanics and microphotonics investigations are shown. The aim of this work is to give a picture of the innovation introduced by exploring the combination of chirality, self-organization and solid structure.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":"4 1","pages":"59 - 79"},"PeriodicalIF":5.1,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2016.1193065","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60431096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-01-02DOI: 10.1080/21680396.2016.1183151
L. V. Mirantsev, E. D. de Oliveira, I. N. de Oliveira, M. Lyra
ABSTRACT The present review is devoted to recent studies of structures with topological defects on nematic liquid crystal (NLC) shells of different shapes and to the possibility of using external electric fields to manipulate these structures. It is shown that principal curvatures of bounding surfaces have a strong effect on the number and arrangement of these defects on NLC shells. It is also shown that external electric fields can be used to control the number of valence centers occurring on these shells, thus unveiling their capability of acting as multivalent building blocks for nanophotonic devices.
{"title":"Defect structures in nematic liquid crystal shells of different shapes","authors":"L. V. Mirantsev, E. D. de Oliveira, I. N. de Oliveira, M. Lyra","doi":"10.1080/21680396.2016.1183151","DOIUrl":"https://doi.org/10.1080/21680396.2016.1183151","url":null,"abstract":"ABSTRACT The present review is devoted to recent studies of structures with topological defects on nematic liquid crystal (NLC) shells of different shapes and to the possibility of using external electric fields to manipulate these structures. It is shown that principal curvatures of bounding surfaces have a strong effect on the number and arrangement of these defects on NLC shells. It is also shown that external electric fields can be used to control the number of valence centers occurring on these shells, thus unveiling their capability of acting as multivalent building blocks for nanophotonic devices.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":"4 1","pages":"35 - 58"},"PeriodicalIF":5.1,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2016.1183151","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60430986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2016-01-02DOI: 10.1080/21680396.2016.1157768
I. Muševič
ABSTRACT This review presents the main results that were achieved over the past decade in the new field of liquid-crystal micro-photonics. After a general introduction to some aspects of state-of-the-art micro-photonics technologies, nematic colloids are discussed in terms of their self-assembly and photonic properties. Liquid-crystal lasers, based on spatially periodic, liquid-crystal phases, are reviewed, and microlasers based on liquid-crystal microdroplets are presented and discussed. We show that optical microfibres can be self-grown in water/liquid-crystal dispersions and present their waveguiding and lasing properties. The review concludes with a discussion of the resonant transfer of light across different liquid-crystal micro-objects and presents the ultra-fast optical Kerr and STED effects in bulk nematic liquid crystals.
{"title":"Liquid-crystal micro-photonics","authors":"I. Muševič","doi":"10.1080/21680396.2016.1157768","DOIUrl":"https://doi.org/10.1080/21680396.2016.1157768","url":null,"abstract":"ABSTRACT This review presents the main results that were achieved over the past decade in the new field of liquid-crystal micro-photonics. After a general introduction to some aspects of state-of-the-art micro-photonics technologies, nematic colloids are discussed in terms of their self-assembly and photonic properties. Liquid-crystal lasers, based on spatially periodic, liquid-crystal phases, are reviewed, and microlasers based on liquid-crystal microdroplets are presented and discussed. We show that optical microfibres can be self-grown in water/liquid-crystal dispersions and present their waveguiding and lasing properties. The review concludes with a discussion of the resonant transfer of light across different liquid-crystal micro-objects and presents the ultra-fast optical Kerr and STED effects in bulk nematic liquid crystals.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":"4 1","pages":"1 - 34"},"PeriodicalIF":5.1,"publicationDate":"2016-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2016.1157768","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60430954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-06-15DOI: 10.1080/21680396.2015.1061958
Sandeep Kumar, Ashwathanarayana Gowda
Analogous to rod-shaped and disc-shaped molecules, bent-core molecules also exhibit nematic phases, in addition to other higher order mesophases. Presently, about 600 bent-core or banana-shaped molecules are known to exhibit nematic phases. In this article, the chemistry and mesomorphic properties of all these materials are summarized.
{"title":"The chemistry of bent-core molecules forming nematic liquid crystals","authors":"Sandeep Kumar, Ashwathanarayana Gowda","doi":"10.1080/21680396.2015.1061958","DOIUrl":"https://doi.org/10.1080/21680396.2015.1061958","url":null,"abstract":"Analogous to rod-shaped and disc-shaped molecules, bent-core molecules also exhibit nematic phases, in addition to other higher order mesophases. Presently, about 600 bent-core or banana-shaped molecules are known to exhibit nematic phases. In this article, the chemistry and mesomorphic properties of all these materials are summarized.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":"3 1","pages":"145 - 99"},"PeriodicalIF":5.1,"publicationDate":"2015-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2015.1061958","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60430807","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-23DOI: 10.1080/21680396.2015.1043658
L. Lucchetti, F. Simoni
We present a review of the main results reported during about two decades on light-induced phenomena in liquid crystal samples doped by the azo-dye Methyl-Red. The aim is to give a unifying picture of the different observed effects which have been demonstrated to be originated form the competition of light-induced adsorption and desorption phenomena at the illuminated boundary surface. They give rise either to colossal nonlinearity or to light-induced anchoring and memory effects and have a potential interest for photonics applications.
{"title":"Light-induced adsorption and desorption in Methyl-Red-doped liquid crystals: a review","authors":"L. Lucchetti, F. Simoni","doi":"10.1080/21680396.2015.1043658","DOIUrl":"https://doi.org/10.1080/21680396.2015.1043658","url":null,"abstract":"We present a review of the main results reported during about two decades on light-induced phenomena in liquid crystal samples doped by the azo-dye Methyl-Red. The aim is to give a unifying picture of the different observed effects which have been demonstrated to be originated form the competition of light-induced adsorption and desorption phenomena at the illuminated boundary surface. They give rise either to colossal nonlinearity or to light-induced anchoring and memory effects and have a potential interest for photonics applications.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":"3 1","pages":"79 - 98"},"PeriodicalIF":5.1,"publicationDate":"2015-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2015.1043658","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60430753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-01-02DOI: 10.1080/21680396.2015.1030461
G. Klimusheva, T. Mirnaya, Y. Garbovskiy
Metal alkanoates combine simple chemical structures and a versatility of condensed states of matter they exhibit. Solid crystals, plastic crystals, lyotropic and thermotropic ionic liquid crystals, liquids, mesomorphic glasses, and Langmuir–Blodgett films are just a few examples. Liquid crystal phases of metal alkanoates are the most intriguing because they represent a non-conventional class of materials known as ionic metallomesogens. Structural, thermal, and transport properties of mesomorphic metal alkanoates are well documented and reviewed. On the contrary, the optical and nonlinear-optical properties of these materials are very poorly understood. The situation has changed rapidly during the last decade. Advances in the design of mesomorphic glasses stable at room temperatures have launched a new era of research in the field of photonic and optoelectronic materials based on mesomorphic metal alkanoates. This manuscript reviews recent developments in the field of optical and nonlinear-optical materials based on mesomorphic metal alkanoates.
{"title":"Versatile nonlinear-optical materials based on mesomorphic metal alkanoates: design, properties, and applications","authors":"G. Klimusheva, T. Mirnaya, Y. Garbovskiy","doi":"10.1080/21680396.2015.1030461","DOIUrl":"https://doi.org/10.1080/21680396.2015.1030461","url":null,"abstract":"Metal alkanoates combine simple chemical structures and a versatility of condensed states of matter they exhibit. Solid crystals, plastic crystals, lyotropic and thermotropic ionic liquid crystals, liquids, mesomorphic glasses, and Langmuir–Blodgett films are just a few examples. Liquid crystal phases of metal alkanoates are the most intriguing because they represent a non-conventional class of materials known as ionic metallomesogens. Structural, thermal, and transport properties of mesomorphic metal alkanoates are well documented and reviewed. On the contrary, the optical and nonlinear-optical properties of these materials are very poorly understood. The situation has changed rapidly during the last decade. Advances in the design of mesomorphic glasses stable at room temperatures have launched a new era of research in the field of photonic and optoelectronic materials based on mesomorphic metal alkanoates. This manuscript reviews recent developments in the field of optical and nonlinear-optical materials based on mesomorphic metal alkanoates.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":"3 1","pages":"28 - 57"},"PeriodicalIF":5.1,"publicationDate":"2015-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2015.1030461","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60430533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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