Download or read book Nonlinear Optical Responses of Blue Phase Liquid Crystals and Their Applications written by Tsung Jui Ho and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Are they called blue phases because they are in blue color? This is the most common question asked by many people. The answer is yes but no. The name was given by the scientist who first observed the special liquid crystalline phase reflecting the color blue, however, the reflection color does not represent the phases. The major difference of blue-phase liquid crystal from other phases is their self-assembly three-dimensional photonic crystalline structure with a lattice constant typically around hundreds of nanometers, and their ability to show Bragg reflection over the visible spectrum.At first, blue-phases were not popular because they are optically isotropic, i.e. no birefringence. However, they attracted wide attention over academic or industrial studies owing to their unique optical properties, such as a fast response time, being polarization- free, possessing no restriction on thickness, and having a self-assembly 3-D structure. Nowadays, scientists in chemistry are able to expand the temperature range from 1 K to almost 100 K and cover the room temperature. Therefore, blue phases are shown to be a promising material to overcome the disadvantage of typical liquid crystal materials.In this dissertation, I will present a comprehensive study of nonlinear optical properties in blue-phase liquid crystal as well as their applications. First, ultrafast optical response of BPLC will be introduced. The results showed that pure transparent BPLC is capable of significantly attenuating a picosecond laser pulse with very high intensity. The mechanism is Maxwell stress-induced flow-reorientation effect. Owing to its tightly bounded structure, BPLC is a promising material for optical switching or optical limiter devices.Furthermore, a detailed study of all-optical image processing with dye-doped BPLC will be revealed. Unlike typical nematic liquid crystals, blue phases are not restricted to sample thickness, and, therefore, Bragg grating condition can be applied to BPLC. The results showed that the diffraction efficiency of BPLC under holographic setup can provide results nearly one hundred times greater than that of the case with nematic liquid crystal. The high diffraction efficiency makes BPLC capable of many different applications, such as hologram reconstruction, phase conjugation, or photorefractive effect. Moreover, an interesting and simple way to prolong the grating memory is discovered, and the detaildynamical studies are shown in the dissertation.
Download or read book Liquid Crystals written by Iam-Choon Khoo and published by John Wiley & Sons. This book was released on 2022-01-26 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: The latest edition of the leading resource on the properties and applications of liquid crystals In the newly revised Third Edition of Liquid Crystals, Professor Iam Choon Khoo delivers a comprehensive treatment of the fundamentals and applied aspects of optical physics, light scattering, electro-optics, and non-linear optics of liquid crystals. The book's opening chapters include coverage of the foundational physics and optical properties of liquid crystals and lead to more advanced content on the display, photonics and nonlinear optics applications of liquid crystals. New topics, including photonic crystals, metamaterials, ultrafast nonlinear optics, and fabrication methods for massive cholesteric and blue phase liquid crystals are discussed at length. Analytical methods and experimental observations of nonlinear light propagation through liquid crystalline and anisotropic materials and devices are also discussed. Liquid Crystals offers an insightful and unique treatment of the nonlinear optics of liquid crystals. New and expanded sections round out this new edition and add to the most up-to-date resource on this topic available today. The book also includes: A thorough introduction to liquid crystals, including their molecular structures, chemical compositions, order parameter, phase transition, and free energies Practical discussions of nematic, cholesteric, smectic, and ferroelectric liquid crystals, and explorations of linear and nonlinear light scattering in these phases. A detailed quantum mechanical treatment of the linear and nonlinear electronic optical response of liquid crystal molecules to optical fields. A self-contained discussion of the fundamentals of nonlinear optics/photonics and comprehensive review of all liquid crystalline materials-based nonlinear optical processes and applications. The latest edition of Liquid Crystals is an indispensable resource for graduate students, professors, research scientists and engineers in industrial or government laboratories. It's also an ideal reference for anyone seeking a one-stop textbook with complete coverage of the optical, electro-optical, and non-linear optical properties and processes of liquid crystals.
Download or read book Optics And Nonlinear Optics Of Liquid Crystals written by Iam-choon Khoo and published by World Scientific. This book was released on 1993-04-28 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a monograph/text devoted to a detailed treatment of the optical, electro-optical and nonlinear optical properties of all the mesophases of liquid crystals and related processes, phenomena and application principles. Quantitative data on material and optical parameters spanning the ultraviolet, visible, infrared as well as the microwave regimes are presented along with detailed theoretical treatments of basic liquid crystal physics, material properties and nonlinear optics.Starting with a discussion on the basic building blocks of liquid crystalline molecules, the authors proceed to present in a pedagogical manner current theories, experiments, and applications of these unique and important optical properties of liquid crystals. Numerous tables of hard-to-find liquid crystalline parameters, a self-contained chapter on general nonlinear optics, and comprehensive literature review are also included.
Download or read book Unconventional Liquid Crystals and Their Applications written by Wei Lee and published by Walter de Gruyter GmbH & Co KG. This book was released on 2021-07-19 with total page 581 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work focuses on recent developments of the rapidly evolving field of Non-conventional Liquid Crystals. After a concise introduction it discusses the most promising research such as biosensing, elastomers, polymer films , photoresponsive properties and energy harvesting. Besides future applications it discusses as well potential frontiers in LC science and technology.
Download or read book Photoinduced Modifications of the Nonlinear Optical Response in Liquid Crystalline Azopolymers written by Raquel Alicante and published by Springer Science & Business Media. This book was released on 2012-10-02 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear optical (NLO) phenomena such as frequency conversion have played a key role in the development of photonic technologies. This thesis reports a detailed study of the molecular response of a large variety of push-pull organic compounds using the Second Harmonic Generation technique, which will serve as a starting point for the investigation at the macroscopic scale of azobenzene-based liquid crystalline polymeric films and their blends with highly efficient NLO chromophores. These materials are designed with the aim of exploiting their photoadressability in order to tailor their nonlinear behaviour. The magnitude and symmetry of their NL response was successfully controlled via light irradiation and thermal treatments. Moreover, as a specific application, the recording of efficient NLO gratings was achieved.
Download or read book Nonlinear Optical Properties of Liquid Crystals and Polymer Dispersed Liquid Crystals written by Francesco Simoni and published by World Scientific. This book was released on 1997 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph is devoted to a detailed treatment of the nonlinear optical properties of liquid crystals. The basic concepts of director optical reorientation and thermal nonlinearities are presented showing the fundamental theoretical approaches and describing the main experimental observations. The presentation is self-consistent and tutorial although the subject matter is of current research interest.The last part of the book deals with more recent results on new composite materials: Polymer Dispersed Liquid Crystals (PDLC). A general presentation of the optical properties is given and the observations of several nonlinear optical effects are reported.
Download or read book Opticals Effects in Liquid Crystals written by I. Jánossy and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1988 physicists and chemists commemorated the centenary of the discovery of the first liquid crystals. Fora long period after this discovery, although many significant results were found, liquid crystal research remained a marginal topic of condensed matter physics. The situation changed in the sixties. At that time the remarkable electro-optical properties of liquid crystals were recognized and found soon widespread application in numeric displays. From a more fundamental point of view, the interest in disordered systems. increased in general at the same time. Liquid crystals represented an important dass of such systems. Among others, phase transitions, hydrodynamics and topological defects occurring in them attracted considerable attention. The connection between the liquid-crystalline state and the structure of biological membranes stimulated a Iot of works also. In the present volume we discuss a relatively new and rapidly developing branch of the fi. eld, namely nonlinear optical effects in liquid crystals. Optical studies have always played a signifi. cant role in liquid crystal science. Research of optical nonlinearities in liquid crystals began at the end of the sixties. Since then it became a powerful tool in the investigation of symmetry properties, interfacial phenomena or dynamic behaviour. Furthermore, several new aspects of nonlinear processes were demonstrated and studied extensively in liquid crystals. The subject covered in this book is therefore of importance both for liquid crystal research and for nonlinear optics itself. The term "nonlinear optics" is used here in a broad sense.
Download or read book Nonlinear Optical Processes In Liquid Crystals And Applications In Optical Switching written by Shuo Zhao and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation research completes the exploration and development of the theoretical framework for collective liquid crystalline optical nonlinearities capable of response speeds in the microseconds -- nanoseconds scale, which is more than 1000 times faster than the conventional liquid crystal (LC) response speed. Also explored in this dissertation are utilizations of these new discoveries to achieve all-optical switching.This work demonstrates all-optical switching using nonlinear orientational and thermal effects, respectively, in pure and dye-doped twisted nematic liquid crystal (TNLC) cells set between crossed polarizers. In the former case, the flow of liquid crystal molecules is generated by Maxwell stress and thereby exerts a torque on the liquid crystal. The resulting reorientation changes the effective birefringence of the liquid crystal, affecting the overall transmission. In dye-doped twisted nematics, the absorption of dye enhances laser heating in the liquid crystal, which leads to reduction of the order parameter and the corresponding macroscopic birefringence, finally making the transmission drop to zero. Following the sequences of these processes, detailed modeling for collective responses of liquid crystal and the time evolution of transmissions under short laser pulses are presented. Besides theoretical description and modeling, we demonstrate the nonlinear optical switching experimentally. The switching threshold and time are consistent with the simulation results. While dye-doped liquid crystals have a low threshold for nonlinear switching, pure twisted nematics possess high transparency in the entire visible and near-infrared spectrum. These findings are believed to advance the current arsenal of high-performance materials for integration/use in advanced optical systems designed for sensor protection; laser hardening; and other beam/image switching, sensing, and processing operations.
Download or read book Liquid Crystalline Fibers Nonlinear Optics written by and published by . This book was released on 1997 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research program consists of experimental and theoretical investigation of several recently observed novel nonlinear optical phenomena occurring in liquid crystal optical fibers and fiber arrays, and to explore their possible applications in fast all-optical switches, limiters, modulators, phase conjugator, and optical storage. This research program has addressed the following problems:- (i) fabrication of isotropic liquid crystals cored optical fibers and thin films of aligned nematic liquid crystals; (ii) Use of special dopants such as dyes and Fullerene C6O were used in conjunction with bias field create molecular realignment and modify the nonlinear electrooptical responses of the liquid crystal cells; (iii) detailed characterization of the optical, and nonlinear optical properties of these liquid crystalline optical elements including propagation mode structures, transmission, nonlinear optical mechanisms in the nanosecond and shorter time regime; and, (iv) detailed studies of optical limiting, stimulated scatterings, phase conjugations, nonlinear absorption, photoconductivity and photorefractivity in these liquid crystal fibers.
Download or read book Liquid Crystals written by Pankaj Kumar Choudhury and published by BoD – Books on Demand. This book was released on 2018-02-28 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid crystals exhibit amazingly interesting properties that make them indispensable for several technological applications. The book Liquid Crystals - Recent Advancements in Fundamental and Device Technologies is aimed to focus on various aspects of research and development that liquid crystal mediums have come across in recent years. This would be ranging from the physical and chemical properties to the important applications that the liquid crystals have in our everyday life. It is expected that the book will make the expert researchers to be abreast of recent research advancements, whereas the novice researchers will benefit from both the conceptual understanding and the recent developments in the area. Multitudes of research themes and directions pivoted to liquid crystals remain the essence, which the readers would get the glimpse of and move ahead for further investigations.
Download or read book Novel Liquid Crystalline Structure for Nonlinear Optics written by and published by . This book was released on 1996 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: This effort consisted of both theoretical and experimental studies of several novel nonlinear optical phenomena in liquid crystal fiber structure and thin films, exploring their potentials for nonlinear-, electro- and adaptive-optical applications. Continuous and pulsed lasers with pulse durations spanning the nanosecond (ns) to picosecond (ps) regime were employed to study these processes in both the ordered (nematic) and the isotropic (liquid) phases of liquid crystals. The projects completed include: characterization of optical nonlinearities of these liquid crystalline materials, studies of coherent beam amplification, phase conjugation effects, and quantitative characterization of their responses with ns and Ps laser pulses. The nonlinear fiber arrays were shown to be capable of good quality image transmission while serving as an optical limiter for short intense pulses throughout the visible spectrum. This research program has also resulted in the discovery of orientational photorefractive effects which will be relevant to current research and development in adaptive optics and holographic storage systems.
Download or read book Liquid Crystals written by Shri Singh and published by World Scientific. This book was released on 2002 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid crystals are partially ordered systems without a rigid, long-range structure. The study of these materials covers a wide area: chemical structure, physical properties and technical applications. Due to their dual nature -- anisotropic physical properties of solids and rheological behavior of liquids -- and easy response to externally applied electric, magnetic, optical and surface fields liquid crystals are of greatest potential for scientific and technological applications. The subject has come of age and has achieved the status of being a very exciting interdisciplinary field of scientific and industrial research. This book is an outgrowth of the enormous advances made during the last three decades in both our understanding of liquid crystals and our ability to use them in applications. It presents a systematic, self-contained and up-to-date overview of the structure and properties of liquid crystals. It will be of great value to graduates and research workers in condensed matter physics, chemical physics, biology, materials science, chemical and electrical engineering, and technology from a materials science and physics viewpoint of liquid crystals.
Download or read book Submillisecond response Blue Phase Liquid Crystals for Display Applications written by Kuan-Ming Chen and published by . This book was released on 2012 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: With exploding growth of information exchanges between people, display has become indispensable in our daily lives. After decades of intensive research and development in materials and devices, and massive investment in manufacturing technologies, liquid crystal display (LCD) has overcome various obstacles and achieved the performance we need, such as wide viewing angle, high contrast ratio, and high resolution, etc. These excellent performances make LCD prevailed in every perspective. Recently, with the demands of energy conservation, a greener LCD with lower power consumption is desired. In order to achieve this goal, new energy-effective driving methods, such as field sequential color display, have been proposed. However, in order to suppress color breakup the LC response time should be faster than 1 ms. To overcome this challenge, various fast-response liquid crystal modes, such as thin cell gap, low viscosity materials, overdrive and undershoot voltages, polymer stabilization, and ferroelectric liquid crystal, are under active investigations. Among these approaches, blue phase liquid crystal (BPLC) shows a greater potential with less fabrication limitations. In this dissertation, the feasibility of polymer-stabilized blue phase liquid crystal for display applications is explored starting from the building blocks of the material system, polymer-stabilization processes, test cell preparations, electro-optical (EO) properties, to suggested approaches for further improvements. Because of the nature of blue phase liquid crystals, delicate balance among system components is critically important. Besides the properties of each composition, the preparation process also dictates the EO performance of the self-assembled nano-structured BPLC composite. After the preparation of test cells, EO properties for display applications are investigated and results described. Approaches for further improvements of the EO properties are also suggested in the final part of this dissertation.
Download or read book Optical Applications of Liquid Crystals written by L Vicari and published by CRC Press. This book was released on 2016-04-19 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, there has been increasing activity in the research and design of optical systems based on liquid crystal (LC) science. Bringing together contributions from leading figures in industry and academia, Optical Applications of Liquid Crystals covers the range of existing applications as well as those in development. Unique in its thorou
Download or read book Selected Papers on Liquid Crystals for Optics written by Stephen D. Jacobs and published by . This book was released on 1992 with total page 736 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamic Light Scattering and Nonlinear Optics in Liquid Crystals written by Amit Agarwal and published by LAP Lambert Academic Publishing. This book was released on 2010-09 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid crystals are known for their fascinating optical properties. This work describes the experiments on light scattering and theoretical calculations on nonlinear optics in liquid crystals. Light scattering is a powerful tool to study the viscoelastic response of liquid crystals which is an essential parameter for display industry. Both thermotropic and lyotropic systems were probed by light scattering. Thermal nonlinearities in cholesteric liquid crystals are described in this book and various surprising liquid crystal phase transitions in the presence of a laser beam are reported. The work described in the book is based on Ph.D. work carried out by Amit K Agarwal at the Raman Research Institute, India and all intellectual and other legal rights arising out of this work are owned by the Institute and they are acknowledged and protected.
Download or read book The Orientational Optical Nonlinearity of Liquid Crystals written by N. V. Tabiryan and published by CRC Press. This book was released on 1986 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
