Uniform and fast switching of window-size smectic A liquid crystal panels utilising the field gradient generated at the fringes of patterned electrodes

A method to enable smectic A (SmA) liquid crystal (LC) devices to switch uniformly and hence fast from the clear state to a scattered state is presented. It will allow the reduction of the switching time for a SmA LC panel of 1x1 m2 changing from a clear state to a fully scattered state by more than three orders to a few tens of milliseconds. Experimental results presented here reveal that SmA LC scattering initiates from the nucleated LC defects at the field gradient of the applied electric field usually along the edges of the panel electrode and grows laterally to spread over a panel, which takes a long time if the panel size is large. By patterning the electrodes in use, it is possible to create a large number of field gradient sites near the electrode discontinuities, resulting in a uniform and fast switching over the whole panel and the higher the pattern density the shorter the panel switching time. For the SmA LC panels used here, the ITO transparent electrodes are patterned by laser ablation and photolithography, respectively. It is shown that the defect nucleation time is much shorter than the growth time of the scattered region, hence it is possible to use the density of the field gradient sites to control the uniformity and switching time of a panel. Furthermore, the patterned SmA panels have a lower switching voltage than that of the non-patterned ones in general.The authors would like to thank the UK Engineering and Physical Sciences Research Council (EPSRC) for the support through the Platform Grant for Liquid Crystal Photonics (EP/F00897X/1) and Dr Anthony Davey for providing the organic SmA LC and Dow Corning Corp. for providing the siloxane-based SmA LC used in this study. The authors would also like to thank Dr Stuart Speakman for the helpful discussions.This is the final version of the article. It first appeared from Taylor & Francis via http://dx.doi.org/10.1080/02678292.2016.114201

High-birefringence nematic liquid crystal for broadband THz applications

Liquid crystals (LCs) have been studied extensively in the visible range for their dielectric tunability, and the characterisation in the terahertz (THz) range has gained increasing interest due to the need for active THz modulation and switching devices. In this paper, we use THz time-domain spectroscopy to measure the frequency-dependent birefringence and the absorption coefficient of a number of commercial and non-commercial nematic LCs, including E7, BL037, MDA-98-1602, LCMS-107, GT3-23001 and 1825, over a range of bias voltages at room temperature. Furthermore, several basic components of LC mixture are analysed to establish their contributions to birefringence and theoretical model is used to fit the absorption spectra. The large tunability and low loss measured for a range of samples show that the LCs are useful tunable dielectrics for compact, efficient and broadband THz devices.The authors would like to thank the UK Engineering and Physical Sciences Research Council (EPSRC) for the support through the Platform Grant for Liquid Crystal Photonics (EP/F00897X/1).This is the final version of the article. It first appeared from Taylor & Francis via https://doi.org/10.1080/02678292.2016.115373

Pixel-level tunable liquid crystal lenses for auto-stereoscopic display

Mobile video and gaming are now widely used, and delivery of a glass-free 3D experience is of both research and development interest. The key drawbacks of a conventional 3D display based on a static lenticular lenslet array and parallax barriers are low resolution, limited viewing angle and reduced brightness, mainly because of the need of multiple-pixels for each object point. This study describes the concept and performance of pixel-level cylindrical liquid crystal (LC) lenses, which are designed to steer light to the left and right eye sequentially to form stereo parallax. The width of the LC lenses can be as small as 20-30 μm, so that the associated auto-stereoscopic display will have the same resolution as the 2D display panel in use. Such a thin sheet of tunable LC lens array can be applied directly on existing mobile displays, and can deliver 3D viewing experience while maintaining 2D viewing capability. Transparent electrodes were laser patterned to achieve the single pixel lens resolution, and a high birefringent LC material was used to realise a large diffraction angle for a wide field of view. Simulation was carried out to model the intensity profile at the viewing plane and optimise the lens array based on the measured LC phase profile. The measured viewing angle and intensity profile were compared with the simulation results.Kun Li ; Brian Robertson ; Mike Pivnenko ; Daping Chu ; Jiong Zhou and Jun Yao "Pixel-level tunable liquid crystal lenses for auto-stereoscopic display ", Proc. SPIE 9005, Advances in Display Technologies IV, 900505 (February 25, 2014); doi:10.1117/12.2039065; http://dx.doi.org/10.1117/12.2039065 Copyright 2014, Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited

Dielectric anisotropy of nematic liquid crystals loaded with carbon nanotubes in microwave range

Liquid crystals are attractive materials for microwave applications as tunable dielectrics owing to low losses and high anisotropy of dielectric properties. The possibility of further enhancing their dielectric anisotropy is studied by loading with highly polarisable and anisotropic rods–carbon nanotubes at various concentrations. The studies are performed using two different methods, one in the range 1–4 GHz and the other at 30 GHz. More than two times increase of microwave dielectric anisotropy in liquid crystals is reported when loaded with 0.01%wt of carbon nanotubes, which is a metastable suspension and 28% increase in an equilibrated suspension. The stability of the LC-CNT composites is discussed

Fast bistable intensive light scattering in helix-free ferroelectric liquid crystals.

A new type of ferroelectric liquid crystal (FLC) is considered, where the reorientation of the director (main optical axes) at the interaction of an electric field with the FLC's spontaneous polarization is due to the movement of spatially localized waves with a stationary profile: solitons arise at the transition due to the Maxwellian mechanism of energy dissipation. Under certain conditions, the appearance of such waves leads to the formation of a structure of transient domains, and as a consequence, to the scattering of light. The Maxwellian mechanism of energy dissipation allows one to reduce the electric field strength at which the maximum efficiency of light scattering is achieved down to 2-3 V/μm and to increase the frequency of light modulation up to 3-5 kHz. Intensive bistable light scattering in an electro-optical cell filled with a specially designed helix-free FLC was studied, and a stable scattering state can be switched on and off for a few tens of microseconds and memorized for a few tens of seconds.Russian Academy of SciencesThis is the author accepted manuscript. The final version is available from The Optical Society via http://dx.doi.org/10.1364/AO.55.00348

THE MISSION OF THE REGIONAL UNIVERSITY AND ITS FOCUS ON THE DEVELOPMENT OF HUMAN CAPITAL IN THE REGION

The purpose of the article: The article clarifies and justifies the mission of a modern regional university, which focuses on the activities of a university on the development of human capital in the region.Materials and methods: Based on the data of scientific literature, strategic documents of the state, materials of regional statistics, surveys of respondents, the strategic direction of the formation of a regional university is justified - orientation of its mission, research and educational activities on the development of human capital. A range of directions for improving the functioning of a regional university has been proposed and justified in order to bring the content of its activities in line with the regional focus and the new mission.Results of the research: Regional universities are presented in the article as high-tech educational organizations of higher education, the vector of strategic development of which should be focused on maximum integration into the economy and social sphere of the regions. Structural components of human capital are proposed - education capital, health capital, labor, cultural and moral capital, intellectual capital, entrepreneurial capital, social capital, cyclically interacting with each other in the process of personal and professional development of a teacher. Applications: This research can be used for universities, teachers, and students. Novelty/Originality: In this research, the model of The mission of the regional university and its focus on the development of human capital in the region is presented in a comprehensive and complete manner

Advanced die-level assembly techniques and quality analysis for phase-only liquid crystal on silicon devices

In this article, quality analysis of the assembled phase-only liquid crystal on silicon devices is presented ba sed on experiences using the flexibility and scalability of die-level assembly process. The research contents mainly consist of quality control and optimisation of liquid crystal filling process and device overall quality assessment including the thickness uniformity of liquid crystal layer with post-assembly inspection. To summarise, pre-production prototype phase-only liquid crystal on silicon devices with high quality has been developed in high reproducibility using a die-level assembly process, the robust glue deposition is performed, liquid crystal filling process in isotropic phase is presented and thickness variation can be controlled in the range of γ/4.This work was supported by State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University. It was also supported by National Natural Science Foundation of China (61307077), Beijing Natural Science Foundation (4144076), China Postdoctoral Science Foundation (2013M530613), the UK Engineering and Physical Sciences Research Council (EPSRC) through the Platform Grant in liquid crystal photonics (EP/F00897X/1) and the Cambridge Integrated Knowledge Centre (CIKC) through projects PASSBACK and PASSBACK3

High-resolution patterning of solution-processable materials via externally engineered pinning of capillary bridges

Electronics based on solution-processable materials are promising for applications in many fields which stimulated enormous research interest in liquid drying and pattern formation. However, assembling of structure with submicro/nano-meter resolution through liquid process is very challenge. We show a simple method to rapidly generate polymer structures with deep- submicrometer sized features over large areas. In this method, a solution film is dried on a substrate under a suspended flexible template with groove/ridge surface topography. Upon solvent evaporation, the solution splits in the grooves and forms capillary bridges between the template and substrate, which are firmly pinned by the edges of the template grooves. This groove pinning stabilizes the contact lines, thereby allowing the formation of fine patterned structures with high aspect ratios which were used to fabricate various functional materials and electronic devices. We also produced secondary self-assembled nano-stripe patterns with resolutions of about 50 nm on the primary lines.We would like to thank the UK Engineering and Physical Sciences Research Council (EPSRC) for the support through the EPSRC Centre for Innovative Manufacturing in Ultra Precision (EP/I033491/1) and the support of the Marie-Curie Fellowship (IEF) under the project number 301028