向列相液晶缺陷光子晶体可调谐滤波器的研究

在一维光子晶体中引入向列相液晶作为缺陷层,用电场改变液晶分子的取向,形成光子晶体可调谐滤波器.用传输矩阵法研究了液晶缺陷光子晶体的可调谐滤波特性,模拟计算了电压和液晶材料参数对滤波器透射谱的影响.结果表明,改变电压能容易改变光子晶体滤波器透射峰的位置、强度、个数和带宽,表现出很好的调谐滤波功能.     

Cholesteric liquid crystals for detection of organic vapours

Studies on the use of cholesteric liquid crystals (CLCs) as sensing phase for detection of organic vapours in air are described. Stock solutions of 1.0% (w/v) cholesteryl nonanoate (CN) and cholesteryl chloride (CC) were prepared in tetrahydrofuran. Binary mixtures, with compositions ranging from 0.18 to 0.25% of CC and 0.82–0.75% of CN, respectively, were prepared by appropriate mixing of the stock solutions. Films were cast by pipetting three 10 μl aliquots of the CLC solution mixture onto a glass disk, whose reverse side was made black to absorb unscattered light. The glass disk was adapted to the common end of a bifurcated optical fibre bundle and placed in a glass vial, which provided a headspace of organic vapours. Measurements were carried out at 27±1 °C, a temperature in which the CLC mixtures maintain their liquid crystalline properties. The responses of the CLC mixtures to vapours of ethanol, acetone, benzene, pyridine and hexane were investigated. The colour of the sensing phases depended on their compositions and exposure to organic vapours gives rise to a change in the optical characteristics of liquid crystals. It was found that the CLC layers containing 0.23–0.25% of CC had no significant change in optical properties when exposed to organic vapours and that ethanol did not cause any optical changes in the liquid crystal layers. Benzene as well as hexane always turned all the coloured liquid crystalline layers to colourless. The CLC layers exhibited different behaviours to vapours of acetone and pyridine. For example, the wavelengths of maximum scattering for the 0.19% CC layer were 530 nm in air, 545 nm in pyridine and 580 nm in acetone. The CLC layers showed reversibility. The lifetimes of these layers (interval of time in which the liquid crystalline phase exists, before crystallisation) were investigated by employing acetone and n-hexane vapours. Average lifetimes of 14–15 min were found for films in contact with these vapours, while a lifetime of 205 min was possible when the CLC film was exposed to air.     

胆甾型液晶传感器及其在环境监测中的应用

介绍了胆甾型液晶传感器的工作原理、结构及其在环境监测中的应用。     

Refractive‐index matching between liquid crystals and photopolymers

Abstract— Refractive indices of two photocurable polymers, NOA65 and NOA81 (Norland Optical Adhesive), and two series of Merck liquid crystals, E‐series (E44, E48, and E7) and BL‐series (BL038, BL003 and BL006), and two UCF high‐birefringence liquid‐crystal mixtures were measured using an Abbe refractometer in the visible spectral region and 15–55°C temperature range. Some liquid crystals have excellent index matching with NOA65 in the red, while some fit better in the blue spectral region. To validate this index‐matching property found in the material level, we prepared some polymer‐dispersed liquid‐crystal devices. Good correlations between material and device performances are obtained.     

Simulation of the spatial pattern and band-gap structure of holographic photonic crystals

Simulation software of the spatial pattern and band-gap structure of the holographic photonic crystals is developed for the research—education purposes. Friendly GUI and training technique elaborated. Examples of the 1D–3D model structures of photonic crystals and their transmission spectrums are given. The article is published in the original.     

Electrically commanded surfaces: A new liquid‐crystal‐display concept

Abstract— Fast in‐plane switching of the optic axis was realized in liquid‐crystal displays (LCDs) based on the concept of Electrically Commanded Surfaces (ECS). According to this concept, the liquid‐crystal layer in such a display is aligned by means of thin ferroelectric liquid‐crystal‐polymer (FLCP) film deposited onto the inner side of the display substrates. An electric field, applied normal to the substrates, switches the molecules of the ferroelectric film, representing the commanded surface that, via elastic forces, further transfers to the liquid‐crystal layer. The concept of electrically commanded surfaces opens the door to a new generation of advanced LCDs exhibiting extraordinary performance such as fast in‐plane switching.     

One-dimensional photonic crystal based on nanocomposite of metal nanoparticles and dielectric

One-dimensional photonic crystal made of nanocomposite of metallic nanoparticles and dielectric is investigated. Splitting of photonic band gap into polaritonic and structure band gap and their fusion are predicted. The different behavior of structure gap with variation of nanoparticle concentration is observed. This behavior is determined by relative arrangement of structure and polaritonic gaps in frequency scale. Considered effects give new possibilities for creating photonic crystals with predefined properties.     

基于CAN的SMD晶体自动测控系统的设计

针对SMD晶体器件的生产需求,设计了基于CAN总线的SMD晶体成品器件自动测控系统,文中,对系统的总体方案、所采用的拓扑结构、子节点的硬件设计以及主控软件和子模块控制软件进行了介绍,对CAN控制器、CAN收发器的选型以及应用中所要注意的问题也进行了讨论,在软件设计中,对CAN控制器的应用模式以及通过报文滤波实现报文的单点和多点发送也进行了描述,通过实际运行证明,整个系统在连续工作的情况下,可保证可靠高效的运行状态,满足了SMD晶体成品器件生产中,对自动化设备的运行可靠性和运行效率的要求.     

一维光子晶体液晶微谐振腔的温度特性

在光子晶体中引入液晶缺陷,形成一维光子晶体液晶微谐振腔.用传输矩阵法研究了这种微谐振腔的温度特性,用E1液晶微谐振腔进行了模拟数值计算.计算结果表明,液晶微谐振腔的特性与温度和液晶分子排列密切相关;对于液晶排列沿平行介质表面的微谐振腔,当温度升高时缺陷峰波长向长波长方向漂移,半高宽度增大, 品质因子减小;而液晶排列沿介质表面法向的微谐振腔的温度变化情况则相反;温度灵敏度和透射峰高度均随温度升高而增大.温度特性为非线性关系,并随温度接近液晶相变点而变化迅速,与现有的各向同性材料微谐振腔的温度特性不同.     

常见冰晶粒子散射特性的初步研究

在不考虑吸收情况下，利用光线跟踪法计算了卷云中经常存在的不同形状冰晶的散射相函数。计算结果显示实心柱状冰晶散射相函数的特征是存在２２°晕和４６°峰；空心柱状冰晶则在１２０°处可以见到另外一个峰；而子弹形冰晶在０°和２２°间出现一个附加峰。并用简单的几何分析解释了某些散射特性。     

Ferroelectric liquid crystals: Excellent tool for modern displays and photonics

The ferroelectric liquid crystals, because of their fast electro‐optical response, are one of the most important classes of liquid crystals. Here, in this review, we have summarized the different electro‐optical modes for ferroelectric liquid crystals. Clark–Lagerwall effect (surface stabilized ferroelectric liquid crystal), deformed helix ferroelectric (DHF) effect, electrically suppressed helix (ESH) mode, DHF orientational Kerr effect, and ESH diffraction modes have been discussed. All of the crucial features, that is, optics, electro‐optics, dynamics, and their dependence on material parameters, operational regime, and applications, have been reviewed.     

光子石墨烯多方位探测传感器研究

为了实现多方位的探测,针对光子石墨烯特殊的光传输机制,在了解光子石墨烯谷依赖波束输运的基础上,选择光子石墨烯的相关参数,并设计了合适的结构模型,用COMSOL软件对其进行仿真计算.结果表明:在二维光子石墨烯结构中放置点源,点源发射的光束在平面内可以沿6个方向进行传输,此结构用于传感器即可以实现多方位的探测,可为多方位探测传感器的研制提供新的思路.     

The liquid‐crystalline derivatives of 3,6‐disubstituted cyclohex‐2‐enones

Abstract— A new synthetic approach for the preparation of various mesomorphic chiral and non‐chiral derivatives of cyclohexene, cyclohexane, phenylcyclohexane, or biphenyl with different combinations of cyclic, bridge, terminal fragments and lateral substituents is proposed and realized. Both nematic and smectic liquid‐crystalline compounds were prepared by the transformations of the corresponding 3,6‐disubstituted cyclohex‐2‐enones.     

Chiral liquid‐crystalline 3,6‐disubstituted cyclohex‐2‐enones and their derivatives and the FLC compositions based upon them

Abstract— The synthesis and chemical transformations of the 3,6‐disubstituted cyclohex‐2‐enones into new chiral liquid‐crystalline lateral substituted derivatives of biphenyl, terphenyl, or quaterphenyl are presented. The mesomorphic properties of the prepared compounds and physical and electro‐optical parameters of FLC compositions based upon them are discussed here, emphasizing structure‐property relations.     

Liquid‐crystal‐material technologies for advanced display applications

Abstract— Ions were dissolved into the liquid‐crystal (LC) materials from peripheral materials and were also generated by electric dissociation. Moreover, those ions are partly stabilized in the form of hydrated or solvated ions with polar molecules. As the ions in an LC slab of display panel deteriorate the image quality, it is essential that LC materials be free from mobile ions and be resilent to contamination by ions. Studies on the generation and behavior of ions in LC materials and their influence on display image quality were successfully applied to the development of advanced LC materials featuring high reliability and high purity, as well as low operational voltage, resulting in sophisticated LCDs with high image quality.     

基于Matlab的光子晶体波导仿真研究

本文首先介绍了光子晶体波导的原理,然后分析时域有限差分法微分方程及边界条件,最后运用matlab语言实现二维光子晶体波导的仿真。     

Anisotropic fluorophors for liquid crystal displays

Liquid crystal displays (LCDs) are commonly found in portable equipment. The main criticisms aimed at these displays are their asymmetric angle-of-view and dull grey appearance, which is particularly acute in low ambient lighting. However, by the inclusion of a fluorescent dye, it is possible to fabricate partially-emissive LCDs with a virtually hemispherical angle-of-view. This effect has been demonstrated succesfully for a range of dyes based on the perylene diester chromophor. An energy transfer mechanism between the liquid crystal host and dye molecule has been identified. This effect was used to enhance the fluorescence intensity.     

基于Matlab的光子晶体波导仿真研究

本文首先介绍了光子晶体波导的原理，然后分析时域有限差分法微分方程及边界条件，最后运用matlab语言实现二维光子晶体波导的仿真。     

陀螺 质量声子晶体结构力学研究

声子晶体是由不同材料组成的周期性结构.其显著特点是弹性波在传播时,受其内部结构的作用,在一定频率范围(带隙)内会抑制弹性波的传播,而在其他频率范围(通带)可以无损耗地传播.本文提出并设计一种新型的陀螺-质量声子晶体结构,研究并且分析了不同参数对于陀螺-质量声子晶体结构振动通带的影响,并通过有限次结构数值计算进行验证.     

Photoalignment of nematic liquid crystal on polyamic‐acid‐based soluble polyimide with no side fragments

Abstract— The photoalignment of nematic LC on a layer of newly synthesized UV‐sensitive polyimide without side fragments is reported. The photoaligning polymer advantageously differs from other photoaligning materials because of its extremely low sticking effect and residual DC voltage. These parameters, as well as the UV and thermal stability of the alignment, are not worse than those of rubbed polyimides. At the same time, the new material possesses all the advantages of photoaligning polymers.