Electrically tunable holographic polymer templated blue phase liquid crystal grating

In this paper, we demonstrate an alternative approach to fabricating an electrically tunable holographic polymer tem- plated blue phase liquid crystal grating. This grating is obtained by preforming a polymer template comprised of periodic fringes, and then refilling it with a blue phase liquid crystal. Compared with conventional holographic polymer dispersed liquid crystal gratings, our grating can remarkably reduce its switching voltage from 200 V to 43 V while maintaining a sub-millisecond response time. The holographic polymer templated blue phase liquid crystal （HPTBPLC） grating is free from electrode patterning, thus leading to a lower cost and more flexible applications.

Bichromatic coherent random lasing from dye-doped polymer stabilized blue phase liquid crystals controlled by pump light polarization

In this paper,we investigate the bichromatic coherent random lasing actions from the dye-doped polymer stabilized blue phase liquid crystals.Two groups of lasing peaks,of which the full widith at half maximum is about 0.3 nm,are clearly observed.The shorter-and longer-wavelength modes are associated with the excitation of the single laser dye（DCM） monomers and dimers respectively.The experimental results show that the competition between the two groups of the lasing peaks can be controlled by varying the polarization of the pump light.When the polarization of the pump light is rotated from 0？to 90？,the intensity of the shorter-wavelength lasing peak group reduces while the intensity of the longer-wavelength lasing peak group increases.In addition,a red shift of the longer-wavelength modes is also observed and the physical mechanisms behind the red-shift phenomenon are discussed.

Optical simulation of in-plane-switching blue phase liquid crystal display using the finite-difference time-domain method

The finite-difference time-domain method is used to simulate the optical characteristics of an in-plane switching blue phase liquid crystal display.Compared with the matrix optic methods and the refractive method,the finite-difference timedomain method,which is used to directly solve Maxwell＇s equations,can consider the lateral variation of the refractive index and obtain an accurate convergence effect.The simulation results show that e-rays and o-rays bend in different directions when the in-plane switching blue phase liquid crystal display is driven by the operating voltage.The finitedifference time-domain method should be used when the distribution of the liquid crystal in the liquid crystal display has a large lateral change.

Synthesis and mesomorphic properties of novel tetrafluorinated biphenyl acetylene liquid crystals with a blue phase

Five novel tetrafluorinated biphenyl acetylene molecules containing two chiral centres in the side chain were synthesized. The mesomorphic behaviour of these compounds was characterized by differential scanning calorimetry (DSC) and optical polarizing microscopy. All these compounds exhibit cholesteric and blue phases.

Solid-phase synthesis of Cu2MoS4 nanoparticles for degradation of methyl blue under a halogen-tungsten lamp

The Cu_2MoS_4 nanoparticles were prepared using a relatively simple and convenient solid-phase process, which was applied for the first time. The crystalline structure, morphology, and optical properties of Cu_2MoS_4 nanoparticles were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and UV-vis spectrophotometry. Cu_2MoS_4 nanoparticles having a band gap of 1.66 eV exhibits good photocatalytic activity in the degradation of methylene blue, which indicates that this simple process may be critical to facilitate the cheap production of photocatalysts.

Low voltage transflective blue-phase liquid crystal display with a non-uniform etching substrate

A transflective polymer-stabilized blue-phase liquid crystal display（BP-LCD） with a non-uniform etching substrate is proposed.In-plane switching（IPS） electrodes on the bottom substrate are put on the different gaps,and the bottom substrate between the electrodes is etched into different depths in transmissive（T） and reflective（R） regions.This structure can balance the optical phase retardation in the two regions and is helpful to achieve well-matched voltag-dependent transmittance and reflectance curves.This transflective display has high optical efficiency,a wide viewing angle,and low operating voltage（approximately 6 V）.

曝光工艺对蓝相液晶图案清晰度的影响

为提高图案化蓝相液晶薄膜(Blue Phase Liquid Crystal Film, BPLCF)的边缘分辨率,使图案更清晰,降低制备工艺难度,本文基于硫醇-丙烯酸酯迈克尔加成反应,在恒温下利用分步掩膜曝光的方式设计并制备了图案化BPLCF。首先,观察BPLCF光学特性随迈克尔加成反应过程进行的变化,结合光谱的半峰宽和反射强度,确定BP I织构相对较好的反应时间;接着,根据选定的反应时间,探究在相同紫外曝光时间下,不同曝光强度对BPLCF光学性能和图案分辨率的影响,得到使图案化BPLCF具有清晰图案和高边缘分辨率的最佳紫外曝光强度;最后,根据实验得到的反应时间和紫外曝光强度,制备了具有高分辨率兰花和梅花图案的BPLCF。实验结果表明,在33℃的恒温下,当迈克尔加成反应时间为60 min、紫外曝光强度为30 mW/cm2、曝光时间为15 s时,BP I结构保留完好,BPLCF图案清晰,边界无阴影,对应的中心波长和半峰宽分别为528 nm和53 nm,此时分辨率可达38μm。该研究对于制备高分辨率的蓝相液晶图案及其在信息防伪以及显示领域的应用具有重要意义。

高转换效率腔内倍频外腔面发射蓝光激光器

高功率高光束质量的蓝色激光在激光显示与照明、水下通信和成像、有色金属加工等许多领域具有广泛应用前景.本文利用增益芯片底部的高反镜分布布拉格反射镜、折叠镜以及后端反射镜构成V型谐振腔,通过腔内插入非线性晶体LBO,获得了高转换效率的高功率、高光束质量蓝光输出.实验研究了非线性晶体的长度、基频激光的线宽、倍频走离角的补偿等不同因素对外腔面发射激光器腔内倍频蓝光输出功率的影响.在LBO的Ⅰ类相位匹配条件下,当晶体长度为5 mm,所用双折射滤波片厚度为1 mm时,获得超过6 W的491 nm波长蓝光输出,x和y方向的光束质量M2因子均为1.08,倍频转换效率为63%.

B和P共掺杂石墨相氮化碳的制备及其光催化性能研究

以尿素和二氰胺为前驱体,B_(2)O_(3)为B源,(NH_(4))_(2)HPO_(4)为P源,采用热缩聚法合成了B和P共掺杂石墨相氮化碳(g-C_(3)N_(4)),考察了硼磷掺杂对g-C_(3)N_(4)结构和光催化性能的影响。利用X射线衍射(XRD)、扫描电镜(SEM)、BET比表面积、X射线光电子能谱(XPS)、紫外-可见光(UV-Vis)等手段对样品进行了表征和分析,考察了其可见光下光催化降解亚甲基蓝染料的性能。结果表明:当B_(2)O_(3)掺入量为0.15g,(NH_(4))_(2)HPO_(4)掺入量为1%时,CNBP1%的光催化性能最优。这主要归因于B、P元素的电负性差异有助于强化氮化碳中内建电场强度进而促进光生电子和空穴的有效分离。相比纯CN,CNBP1%表现出松散的片状多孔结构,更窄的禁带宽度和更强的可见光吸收能力。

蓝相液晶对聚集诱导发光分子荧光性能的影响

为了拓宽蓝相液晶的应用范围,构建多功能化蓝相体系平台,本文将具有聚集诱导发光(AIE)特性的液晶TPE-PPE引入蓝相液晶体系,围绕复合体系的荧光性能展开研究。一方面,系统研究并归纳了手性添加剂含量对蓝相液晶相转变行为和光子带隙位移情况的影响;另一方面,探究了蓝相液晶对AIE分子荧光性能的影响,提出了相关荧光增强效应的假说。实验结果表明,不同手性添加剂体系的蓝相Ⅱ的温域范围基本一致,且反射带隙随着温度的降低发生蓝移;而蓝相Ⅰ的温域与手性密切相关,体系中仅存在蓝相Ⅰ时,其反射带隙随温度的降低而红移。蓝相液晶体系对AIE分子有一定的荧光增强效应,并且在整个蓝相温域内,蓝相Ⅰ的反射带隙红移,体系的荧光强度明显增强。由此得出结论,TPE-PPE分子在一定程度上参与了蓝相液晶体系的自组装。由于TPE-PPE分子在双螺旋柱结构中的受限运动,导致其荧光强度增强。随着蓝相Ⅱ的消失和蓝相Ⅰ光子带隙的红移,更多TPE-PPE分子参与到双螺旋柱的自组装中,体系的荧光发射增强。

磷酸铋(BiPO_(4))纳米晶的高温相演变和光催化性能研究

采用室温共沉淀法合成磷酸铋(BiPO_(4))纳米晶,并对其进行不同温度的烧结处理,最后利用X射线粉末衍射(X-ray powder diffraction,XRD)、扫描电子显微镜(scanning electron microscope,SEM)和紫外-可见漫反射吸收光谱(UV visible diffuse reflectance absorption spectroscopy,UV-Vis DRS)对样品的晶体结构、形貌和光学吸收进行表征。结果表明,室温共沉淀合成的样品和600℃烧结所制备的样品结构均为纯低温单斜相的磷酸铋(LT-BiPO_(4)),且两种样品均为单分散米粒状颗粒形貌;在700℃和800℃烧结处理后,低温单斜相的LT-BiPO_(4)可完全转变为高温单斜相的磷酸铋(HT-BiPO_(4)),HT-BiPO_(4)的米粒状颗粒可全部自组装成三维多孔网络结构的形貌;700℃烧结样品光催化降解亚甲基蓝的性能最优,紫外灯照射80分钟(min)后,700℃烧结样品的亚甲基蓝降解率可达76.2%。

Cs_(2)NaGdCl_(6)∶Sb^(3+)荧光粉制备及发光性能

无铅双钙钛矿材料具有高效、稳定的自陷激子发射,在下一代固态照明中显示出巨大的潜力。本文采用微波固相法制备出系列新型的Cs_(2)NaGdCl_(6)∶Sb^(3+)蓝色荧光粉。通过X射线衍射仪、扫描电子显微镜和荧光光谱仪对所制备样品的结晶性、微观形貌和发光性能进行了表征和分析。结果表明,所制备的双钙钛矿型Cs_(2)NaGdCl_(6)∶Sb^(3+)样品属于立方晶系,空间群Fm3m,大小为10μm的不规则颗粒。在336 nm激发光下,荧光粉在460 nm处发射出极强的蓝光,且不同Sb^(3+)离子掺杂浓度的样品色坐标均在蓝光区域。当Sb^(3+)离子掺杂浓度超过0.015时,发生浓度猝灭,归因于电偶极⁃电偶极相互作用。此外,Cs2NaGd0.985Cl6∶0.015Sb^(3+)样品具有较佳的热稳定性,当温度升高至423 K时,发光积分强度仍为323 K时的72.6%。基于上述研究结果,Sb^(3+)离子激活Cs_(2)NaGdCl_(6)蓝色荧光粉在发光二极管领域具有潜在的应用价值。

Nonlinear characterization and optical switching in bromophenol blue solutions

In this paper the results from investigations of the nonlinear refractive index and nonlinear absorption coefficient of Bromophenol Blue using the Z-scan technique with a continuous wave laser beam at wavelengths 488 nm and 514 nm are presented. It was observed that the material exhibited reverse saturation absorption and self defocusing behavior. It was found that the increase in solution concentration resulted in linear increase of the nonlinear refractive index. A pump and probe technique was used to obtain the absorption spectrum of triplet state. Furthermore the nonlinear absorption effect was used to demonstrate all optical switching.

Geometric phases in qubit-oscillator system beyond conventional rotating-wave approximation

In this work we investigated the geometric phases of a qubit-oscillator system beyond the conventional rotating- wave approximation. We find that in the limiting of weak coupling the results coincide with that obtained under rotating-wave approximation while there exists an increasing difference with the increase of coupling constant. It was shown that the geometric phase is symmetric with respect to the sign of the detuning of the quantized field from the one-photon resonance under the conventional rotating-wave approximation while a red-blue detuning asymmetry occurs beyond the conventional rotating-wave approximation.

聚合物稳定双频蓝相液晶的亚微秒电光响应

蓝相液晶由于其出色的电光性质在信息显示和光电子领域受到了广泛的关注,然而日益发展的信息技术对信息的传递、处理、存储速度提出了更高的要求。为了进一步强化蓝相液晶的快速电光响应优势,本文以双频向列相液晶为主体,掺杂聚合单体、手性剂、光引发剂等材料制备了聚合物稳定双频蓝相液晶,通过调节双段电压脉冲时长,实现了聚合物稳定双频蓝相液晶的快速电光调控,其电光调控的开关时间均小于500 ns。

基于维度调制的准二维蓝色钙钛矿发光二极管

金属卤化物钙钛矿(MHP)作为一种新兴的半导体材料,目前已在光电应用中表现出优异的性能。其中,基于MHP的发光二极管(PeLED)发展迅猛,红光和绿光器件的效率已达到商用水平。然而,蓝光PeLED的效率还远落后于红、绿光器件,这在很大程度上阻碍了PeLED在全彩显示领域中的应用。本文通过调节混合卤素阴离子的比例以及准二维钙钛矿组分来实现基于维度调制的准二维蓝色PeLED制备。首先,我们采用在CsPbBr_(3)∶PEABr准二维钙钛矿中添加苯乙基氯化胺(PEACl)逐步替换苯乙基溴化胺(PEABr),实现了发光峰从502 nm到476 nm的可调制发射。然而,随着PEACl的增加,薄膜中的缺陷及n=1低维相逐渐增多,导致器件效率降低。我们将溴化胍(GABr)引入到CsPbBr_(3)∶PEACl准二维钙钛矿中,n=1低维相得到了显著的抑制,这有利于激子能量的转移,最终蓝光范围内准二维PeLED性能得到了显著提升。本工作为实现高效蓝光PeLED提供了新的思路。

西安灞渭滨水区域蓝绿体系规划与分步骤建设实践

城市蓝绿空间是生态优先战略实施过程中的重要议题,其规划旨在合理构建生态结构与格局,为城市生态保护等提供重要支撑。西安灞渭滨水区域蓝绿体系建设是在中华人民共和国第十四届运动会大事件影响下进行的。赛前建设围绕规划核心区域和公共空间的环境提升,重点打造集文化体育场馆、城市公园、市民休闲广场于一体的城市新名片;赛后持续完善基础配套设施,建设滨水生态宜居城市。通过分析西安灞渭滨水空间的现状问题、建设目标,总结分阶段实施的要点步骤,以期在生态文明建设的指引下,从多个维度为类似的城市滨水空间环境营造提供借鉴。

石墨相氮化碳光催化剂制备及降解亚甲基蓝研究

以三聚氰胺与柠檬酸为原料合成了石墨相氮化碳g-C3N4,采用XRD和XPS表征了催化剂结构,以亚甲基蓝溶液为模拟污染物探索了其优化降解工艺。结果表明,成功合成了g-C3N4催化剂。当pH和催化剂投加量为6和1.6 g/L、亚甲基蓝溶液初始质量浓度小于20 mg/L、催化剂循环次数为3时,g-C3N4催化剂光催化性能为佳,降解率可达98%,具有优异的光催化性能。

碳纳米管掺杂聚合物稳定蓝相液晶的电场响应性能

通过将不同尺寸的多壁碳纳米管(MWNTs)掺杂到聚合物稳定蓝相(PSBP)液晶中研究了体系的蓝相温度稳定性和电场响应性能。小尺寸MWNTs的加入使PSBP电诱导反射波谱宽化的阈值电压显著降低。MWNTs掺杂PSBP液晶光子晶体的电响应阈值场强降低至0.1 V/μm,在1.3 V/μm电场下反射光谱谱带宽度可从20 nm拓宽至310 nm。该材料在反射型显示、可调滤光片等领域具有潜在应用价值。

蓝相液晶材料与光子学器件研究进展

蓝相液晶是一种三维手性自组装软超结构材料,具有光学各向同性,选择性反射波长,快速响应等优秀特性,无论在显示还是光子器件的应用上都具有良好的发展前景,吸引了研究人员的大量关注。近十年关于蓝相液晶显示领域的研究与工程或应用发展迅猛,于此同时催生了其在光子学这个后显示领域的研究。面对来自国际上其他先进国家的竞争与压力,中国大陆的学者们奋勇迎接,经过短短数年的发展获得了一批有显示度的成果,在国内外的优秀期刊上报道了一系列富含学术性和实用性的工作。具备高热稳定性与显著电光调制特性的新型蓝相液晶材料及其光子学器件,如衍射光栅、相位调制器、透镜、激光以及光衰减器等,相继被开发出。本文追逐这些前辈留下的脚印,从材料制备、性能到光子器件设计、应用进行了概括性的回顾,旨在通过此综述激发出蓝相液晶在非显示光子学应用领域更多的研究灵感;若能起到进一步促进该领域发展的作用,笔者将感到幸甚之至!