蓝相液晶晶体结构与结构色

蓝相液晶具有许多不同寻常的光学特性,如快速的响应速度(亚毫秒量级),可见光范围的布拉格反射,光学各向同性等。这些特性使得蓝相液晶在电光器件领域有着广泛的应用前景。近年来,除显示领域以外,蓝相液晶在聚合物蓝相液晶薄膜、晶格结构、结构色,以及可调谐方面取得了一系列新的进展。这些进展不仅深化了人们对蓝相液晶制备和基本结构认知,同时也极大扩展了其应用范围。本文侧重阐述近年来蓝相液晶在晶格结构以及结构色方面的研究进展。首先介绍蓝相液晶薄膜的制备方法和进展;其次介绍蓝相液晶晶格结构,包括单畴晶格、单晶晶格和结构色方面的研究进展;最后介绍可调谐的蓝相液晶晶格结构,主要包括电场、光场对蓝相晶格的调控作用。     

液晶光学器件的近红外激光损伤研究进展

液晶光学器件在激光聚变、光电对抗、激光雷达、激光通信等领域的应用面临着近红外高功率激光辐照失效的风险。在介绍液晶光学器件基本结构和基本工作原理的基础上,按照液晶光学器件的组成,依次对构成液晶光学器件的导电膜、取向膜、液晶材料,以及整体液晶光学器件在近红外激光辐照下的损伤特性及机制的研究进展进行了综述。     

液晶光学位相调制及其应用

基于液晶材料的空间光调制器已被广泛地研究并应用于光学信息处理的诸多领域。在这些应用中液晶空间光调制器主要是作为光强度调制。液晶光调制器的基础是液晶的双折射效应,因此液晶光调制器也应当能作为光学位相调制器。我们知道光学位相在现     

液晶的多维度光场调控技术研究进展

液晶作为一种介于液态与结晶态之间的功能性软材料，可以同时表现出液体流动性和晶体的各向异性，被广泛应用于图像显示、集成光电子学、光通信等领域。近年来，由于液晶理论研究的深入及其加工技术的发展，液晶在几何相位、动态可调谐等光场调控方面的优势推动了光学器件的平面化、集成化、智能化和小型化。综述了液晶在光场调控方面的最新应用进展，具体讨论了其对光波振幅、相位、偏振等多维度参数的调控特性，进而探讨了液晶在多功能光学器件和光学加密系统中的应用。     

大口径近红外激光液晶波片研制

介绍了液晶光学器件在高功率激光装置上的应用,设计并制作了通光口径为50mm×50mm的1053nm红外液晶λ/4波片,测量了液晶波片的液晶层厚度、位相延迟和激光损伤阈值.初步验证了液品波片在高功率激光装置上应用的可行性.     

用衰减全反射法对液晶光学性质的研究

液晶作为一种最有前途的平板显示材料,其光学特性及与之相关的分子在液晶盒内的排列特性对显示器件的设计及制作无疑是极为重要的。衰减全反射法(简称ATR方法)最早应用与对金属薄膜特性的研究,后来逐渐成为研究各类介质光学性质的有力工具。最近几年,这种方法在液晶研究领域里展现了强大的活力——它能够测量液晶的光学常数、分析掖晶排列特性、揭示液晶在光场及电场作用下的行为等等。本文介绍了衰减全反射法的基本原理、实验方法及其在研究液晶的光学特性上的应用。     

液晶光学器件激光损伤研究

为了实现液晶光学器件在高功率固体脉冲激光装置上的应用,采用理论模拟和实验相结合的方法研究了液晶光学器件的激光损伤情况,建立了液晶光学器件激光损伤的物理模型,计算了一定入射激光能量密度下液晶光学器件的温度场分布和损伤情况,测量了液晶光学器件中聚酰亚胺薄膜和液晶材料的激光损伤阈值,得到了液晶光学器件的激光损伤机理和损伤阈值。结果表明,液晶光学器件的激光损伤主要源于组成液晶光学器件的聚酰亚胺薄膜和液晶材料因温度升高导致的破坏,通过液晶光学器件结构的合理设计和物理参量的选择可以提高其抗激光损伤能力。     

精确设计衍射光学元件

衍射光学元件的补偿特性,已经极大地增加了人们把这种元件应用在光学系统之中的兴趣。新的计算和制作方法可以简化和最佳化它们的使用。 通常地,衍射结构产生的强烈的色散,限制了衍射光学元件的应用。但当它与折射透镜结合起来应用时,这个缺陷就成为优点。商品化的光学设计软件包,把衍射结构视为表示理想的连续位相轮廓的特殊种类的全息光     

中国物理学会2004秋季学术会议“液晶物理及其应用”分会组委会通知

本次物理学会液晶专业分会的主题为“液晶物理及其应用”,其专业内容涵盖以下各方面:　　1、新型显示模式的研究2、液晶光学器件的研究3、分子场理论及其应用4、弹性连续体理论及其应用5、液晶与取向膜的界面物理6、新型取向方法的研究7、生物膜中的液晶物理8、液晶的光波导技术研究9、新液晶材料的物理特性1 0、液晶的旋光特性研究1 1、新型液晶材料、取向剂材料的制备研究1 2、新概念液晶器件1 3、液晶器件检测技术研究1 4、其他液晶相关的理论与应用研究。希望踊跃投稿。根据中国物理学会组委会的安排,7月1 5日前论文摘要需征集完毕。因…     

信息与动态

中国物理学会2 0 0 4秋季学术会议“液晶物理及其应用”分会组委会通知　　本次物理学会液晶专业分会的主题为“液晶物理及其应用”,其专业内容涵盖以下各方面:　　1、新型显示模式的研究2、液晶光学器件的研究3、分子场理论及其应用4、弹性连续体理论及其应用5、液晶与取向膜的界面物理6、新型取向方法的研究7、生物膜中的液晶物理8、液晶的光波导技术研究9、新液晶材料的物理特性1 0、液晶的旋光特性研究1 1、新型液晶材料、取向剂材料的制备研究1 2、新概念液晶器件1 3、液晶器件检测技术研究1 4、其他液晶相关的理论与应用研究。希望踊…     

光开关在自动交换光网络中的研究与检测技术

作为自动交换光网络中的核心器件,光开关将在未来全光网中发挥着重要作用,并成为未来光联网的关键技术。本文总结光开关实现方法的最新进展,重点介绍电光效应开关和超高速光控开关的工作原理和实际应用。最后阐述我实验室在光开关性能检测方面所做的研究工作.     

Low-loss and low-dispersion-slope highly nonlinear fibers

In recent technologies, various optical signal processing systems have been reported. In many of these applications, highly nonlinear fibers (HNLFs) are used as key parts. Especially, low loss and low dispersion slope are critical features of the HNLFs. In this paper, their design and characteristics, packaging technology, and applications are introduced.     

LCOS技术的发展

介绍了LCOS器件结构,应用中的关键问题。描述了投影显示关键参数（分辩率、对比度、投影光学、系统的光通量、彩色化、灯及屏幕）及优化方法。讨论了有街于研究开发的问题。主要有液晶显示的各种电光效应。     

How far has the molecular alignment of liquid crystals been elucidated?

Liquid crystal displays (LCDs) - born in late 1960s - have become a 45 billion-dollar industry in 2004. Today's LCD panels cover a wide range of sizes from 0.2 to 82 in diagonal. The electro-optical characteristics of any field effect LCD are determined by the orientation of its liquid crystal (LC) molecules at the display boundaries. Until recently most LCD alignment processes were based on rubbing polymer coated LCD substrates with a cloth. Despite its key importance, the complex mechanism governing the alignment of LC molecules on display substrates is still not well understood. Do the microgrooves generated by rubbing induce LC-alignment or does the stretching of polymer chains as a result of brushing cause it? To overcome the drawbacks of conventional aligning techniques, new alignment processes have recently been proposed and developed. Examples are micro embossing, ion bombardment, fringe field effects and photo-alignment. In this paper, some mechanisms of LC alignment are discussed and various alignment techniques and methods to investigate the interaction of LC molecules with substrates are reviewed.     

Model for analyzing manufacturing-induced internal stresses in 50-GHz DWDM multilayer thin-film filters and evaluation of their effects on optical performances

The manufacture of a high-quality reliable thin-film filter (TFF) requires a detailed understanding of the stresses created within the device during fabrication. The ability to systematically approximate the internal stress effect on optical performance is of crucial importance to provide fabrication guidance and improve manufacturing yield. This paper analyzes the internal stress distributions in the substrate and thin-film layers of a 50-GHz TFF and examines the relation of these stresses to the filter's optical characteristics. A linear model along the thickness direction is introduced based upon Townsend's theory of multilayer structures. The analytical results for the key optical parameters are in good agreement with measurements on fabricated filters. This model analyzes the effects of process parameters, such as the substrate type, its coefficient of thermal expansion, and the final substrate thickness on the optical performance of the transmission spectrum center wavelength, transmission passband ripple and isolation, the chromatic dispersion, and polarization-mode dispersion.     

Addition of single-wall carbon nanotubes to a liquid crystal material: Impact on dielectric properties

In this study, the effect of carbon nanotube (CNT) on the dielectric parameters of (11-(4-cyanobiphenyl-4′-oxy)undecan-1-ol) (coded as) LC11 has been investigated by dielectric spectroscopy measurements. According to analysis of ac dielectric parameters׳ analysis, while relaxation frequency increases with CNT doping, the magnitude of energy loss decreases. In this respect, CNT doped LC11 material which can be utilized in the wide working frequency interval with low energy requirements, has a great potential for technological applications. On the other hand, CNT adding changes the relaxation type from nearly Debye to non-Debye type. In addition to these remarkable modifications on the dielectric parameters, it has been determined that CNT doping extends the frequency interval where the liquid crystal (LC) system shows negative dielectric anisotropy (NDA). In other words, observation of the NDA at the higher frequency region relative to LC11 means that the molecular alignment can be controlled by CNT. Hence, tuning the alignment of the LC11 molecules by CNT doping may lead its utility for various LC device applications.     

Quadratic Electro-Optic Kerr Effect: Applications to Photonic Devices

We propose novel applications of the quadratic electro-optic Kerr effect to photonic devices. Specifically in this work, two new illustrative examples are described, namely an electrically controlled multistable switch (ECMS), and an electrically tunable Bragg grating (ETBG). Their functionality is based on the third-order nonlinearity in an isotropic medium. On one hand, we note that the first key feature is the all-optical as well as electro-optical control/tunability. This can be achieved only in the third-order nonlinear material as opposed to a more frequently used linear electro-optic effect exploited in optical crystals. On the other hand, the second important key feature is the availability of integrated and compatible materials that show third order nonlinearity. In the first application proposed here, ECMS, the interplay between the quadratic electro-optic and all-optical Kerr effects is crucial for its tunable operation and leads to an interesting feature of storing an electrical information optically. In the second example, ETBG, employing the quadratic electro-optic effect makes it attractive thanks to the existence of the third-order nonlinearity in many interesting isotropic materials that are suitable for device integration. Devices such as modulators, switches, mixers, variable attenuators or optical limiters can be designed.     

国内大功率半导体激光器研究及应用现状

近年来,国内外在大功率半导体激光器方面的研究均取得了很大的进展。其中,大功率半导体激光器列阵的研究和应用成为最大的亮点,如超高电光转换效率、高亮度和高可靠性等主要光电特性均实现了巨大的突破。针对国内大功率半导体激光器主要研究内容和关键技术进行了总结,在外延片结构中广泛采用应变量子阱结构、无铝有源区宽波导大光腔结构及非对称波导结构来提高端面光学灾变损伤光功率密度,还从腔面光学膜、器件封装、器件可靠性、光束整形与耦合以及器件应用等几个方面给予介绍。     

Design and Simulation of a Narrow Passband Electro-Optical Tunable Filter with Band-pass and Band-rejection Output

An electro-optical tunable filter comprised of two paralleled identical long-period waveguide gratings is proposed in this paper. The filter has one input port and two separate output ports, outputting band-pass and band-rejection light respectively. Using poled electro-optical polymer material to fabricate its waveguide cores enable the filter’s tuning speed to approach nanosecond order. With the aid of long-period waveguide gratings, the tuning range of the filter is Λ times larger than the conventional electro-optical filters. We built up a model to design and simulate the proposed tunable optical filter. We investigate the relationship between the parameters of the long-period waveguide grating and the characteristics of the tunable filter, such as tuning range and FWHM. The simulation results show that the tunable optical filter can realize high-speed tuning in the wavelength range of 1530 nm to 1560 nm, and the FWHM width can reach 0.8 nm. Compared with the conventional optical filters, the results show that a high-speed widely tunable optical filter with narrow pass band can be achieved.     

近零平坦色散三包层光子晶体光纤的设计

为了使光子晶体光纤（PCF）在钛宝石飞秒激光器的工作波长0.80 m 和光通信窗口1.55 m 处获得宽的近零超平坦色散,使用了三包层六角空气孔环结构设计来代替普通的单包层结构。应用了改进的有效折射率法对该三包层PCF 进行了数值模拟。结果表明:三包层PCF 的色散随结构参数的微小变化而有较大的变化,因此通过对PCF 结构参数的合理调节,分别实现了在0.800.02 m 和1.550.15 m 波长范围内近零、平坦色散（色散范围0.5 ps/（kmnm）,色散斜率范围0.02 ps/（kmnm2）的结构设计。这对于光通信系统及研究飞秒激光在PCF 中的传输特性,拓展飞秒激光的研究和应用都具有重要意义。