Colorimetric Determination of Chloridion in Domestic Water Based on the Wavelength Shift of CsPbBr_(3) Perovskite Nanocrystals via Halide Exchange

Cubic phase CsPbBr_(3)perovskite nanocrystals(PNCs)was prepared by a high-temperature hot-injection method.The high photoluminescence quantum yield(PLQY)of as-prepared CsPbBr_(3)PNCs was 87%,which can be used for the determination of chloridion in domestic water samples based on their wavelength-shift characteristics via halide exchange.The proposal approach for the determination of chloridion reveals a linear correlation ranged from 10 to 200μM of the chloridion concentration and the wavelength shift of CsPbBr_(3)PNCs with a correlation coe fficient of R^(2)=0.9956.The as-mentioned method reveals neglectable responses towards those co-existing ions in the water aside from chloridion,due to the quick exchange between Cl and Br and the outstanding color change caused by wavelength shift.The strategy has been applied to the determination of chloridion in water samples with the recoveries of 98.9–104.2%and the limit of detection(LOD)of 4μM.These results show that the suggested approach is promising for the development of novel fluorescence detection for chloridion in water.

An Adjustable Pure Dispersion Slope Compensating-Module without Center Wavelength Shift Based on Strain-Chirped Fiber Bragg Gratings

We demonstrate an adjustable pure dispersion slope compensating-module based on strain-chirped fiber Bragg gratings. The center wavelength of the module is preserved while the pure dispersion slope is tuned.

Maintained Exposure to Spring Water but Not Double Distilled Water in Darkness and Thixotropic Conditions to Weak (~1 µT) Temporally Patterned Magnetic Fields Shift Photon Spectroscopic Wavelengths: Effects of Different Shielding Materials

Spring water but not double-distilled water was exposed, in darkness, to a temporally patterned weak magnetic field that has been shown to affect planarian behavior and slow the rate of cancer cell proliferation. Exposure to the magnetic field caused a reliable shift in the peak (longer) wave-length of ~10 nm for fluorescence emissions and a ~20% increase (~100 counts) in fluorescence intensity. Spectral analyses verified a shift of 5 and 10 nm, equivalent to ~1.5 × 10-20 J “periodicity” across the measured wavelengths, which could reflect a change in the an intrinsic energy as predicted by Del Giudice and Preparata and could correspond to two lengths of O-H bonds. Wrapping the water sample containers during exposure with copper foil, aluminum foil, or plastic altered these fluorescent profiles. The most conspicuous effect was the elimination of a ~280 nm peak in the UV-VIS emission spectra only for samples wrapped with copper foil but not aluminum or plastic. These results suggest that weak magnetic fields produce alterations in the water-ionic complexes sufficient to be reliably measured by spectrophotometry. Because the effect was most pronounced when the spring water was exposed in darkness and was not disturbed the role of thixotropic phenomena and Del Giudice entrapment of magnetic fields within coherent domains of Pollack virtual exclusion zones (EZ) may have set the conditions for subsequent release of the energy as photons.

微小角中子散射谱仪的高分辨中子闪烁体探测器研究

微小角中子散射谱仪是中国散裂中子源(China spallation neutron source,CSNS)工程目前在建的谱仪之一,为了实现微小角散射模式下中子衍射的精确测量,要求中子探测器的位置分辨≤2 mm、探测效率≥60%@0.4 nm。在此物理精度需求下,研制了基于^(6)LiF/ZnS(Ag)闪烁屏、波移光纤阵列和硅光电倍增管(Silicon Photomultiplier,SiPM)结构的位置灵敏型闪烁体探测器,以实现热中子的高效率和高分辨实时探测。探测效率测试以标准3He管的入射中子数归一化计算得到,位置分辨通过含有“CSNS”字样的含硼铝板验证。本文详细研究了0.5 mm直径波移光纤的光传输性能,对比了不同硅光电倍增管的增益和热噪声特性,并以此设计了有效面积为300 mm×300 mm的探测器工程样机。经测试,该探测器的位置分辨为1.2 mm×1.2 mm,探测效率为(61.8±0.2)%@0.4 nm,达到了工程设计指标,满足了CSNS工程微小角谱仪的中子衍射测量需求。

An Ant Colony Algorithm Based on Cross-Layer Design for Routing and Wavelength Assignment in Optical Satellite Networks

This paper introduces an ant colony routing and wavelength assignment algorithm based on cross-layer design(CL-ACRWA),which can overcome the adverse effects of Doppler wavelength shift on data transmission in optical satellite networks. Firstly, a cross-layer optimization model is built, which considers the Doppler wavelength shift, the transmission delay as well as wavelength-continuity constraint. Then an ant colony algorithm is utilized to solve the cross-layer optimization model, resulting in finding an optimal light path satisfying the above constraints for every connection request. The performance of CL-ACRWA is measured by the communication success probability, the convergence property and the transmission delay. Simulation results show that CL-ACRWA performs well in communication success probability and has good global search ability as well as fast convergence speed. Meanwhile, the transmission delay can meet the basic requirement of real-time transmission of business.

Dynamic routing and wavelength assignment algorithm of optical satellite networks based on cross-layer design

In order to overcome the adverse effects of Doppler wavelength shift on data transmission in the optical satellite networks,a dynamic routing and wavelength assignment algorithm based on crosslayer design( CL-DRWA) is introduced which can improve robustness of the network. Above all,a cross-layer optimization model is designed,which considers transmission delay and wavelength-continuity constraint,as well as Doppler wavelength shift. Then CL-DRWA is applied to solve this model,resulting in finding an optimal light path satisfying the above constraints for every connection request. In CL-DRWA,Bellman-Ford method is used to find an optimal route and a distributed relative capacity loss method is implemented to get an optimal wavelength assignment result on the optimal route. Moreover,compared with the dynamic routing and wavelength assignment algorithm based on minimum delay strategy( MD-DRWA),CL-DRWA can make an improvement of 5. 3% on the communication success probability. Meanwhile,CL-DRWA can meet the requirement of transmission delay for real-time services.

Chromatic Dispersion Monitoring Method Based on Phase Shift Technique

The modulation phase shift method was used to measure chromatic dispersion in a standard single mode fiber for telecommunication. The modulation phase difference of the transmitted light at the wavelength of 1532.16 nm modulated by a radio frequency signal was measured, relative to the transmitted light at the wavelength of 1549.33 nm modulated by the same signal. By introducing a reference light at the wavelength of 1310 nm, a 1310/1550 nm wavelength division multiplexing was used instead of the high cost dense wavelength division multiplexing. In the experiment, two testing lights were coupled with the reference light to the fiber spools of different lengths, respectively. By finite difference method, the chromatic dispersion between the two testing lights was measured, and the fixed errors generated during transmission were less than 0.5 ps/(nm·km).

The ac Stark shifts of the terahertz clock transitions of barium

Wavelength-dependent AC Stark shifts and magic wavelengths of the terahertz clock transitions between the metastable triplet states 6s5d3D1 and 6s5d3D2are investigated with considering the optical lattice trapping of barium atoms with the linearly polarized laser. The trap depths and the slopes of light shift difference with distinct magic wavelengths of the optical lattices are also discussed in detail. Several potentially suitable working points for the optical lattice trapping laser are recommended and selected from these magic wavelengths.

Performance optimization of scintillator neutron detectors for EMD in CSNS

Chinese Spallation Neutron Source(CSNS) has successfully produced its first neutron beam in 28th August 2017. It has been running steadily from March, 2018. According to the construction plan, the engineering materials diffractometer(EMD) will be installed between 2019–2023. This instrument requires the neutron detectors with the cover area near3 m2in two 90° neutron diffraction angle positions, the neutron detecting efficiency is better than 40%@1A, and the spatial resolution is better than 4 mm×200 mm in horizontal and vertical directions respectively. We have developed a onedimensional position-sensitive neutron detector based on the oblique6Li F/Zn S(Ag) scintillators, wavelength shifting fibers,and Si PMs(silicon photomultipliers) readout. The inhomogeneity of the neutron detection efficiency between each pixel and each detector module, which caused by the inconsistency of the wave-length shifting fibers in collecting scintillation photons, needs to be mitigated before the installation. A performance optimization experiment of the detector modules was carried out on the BL20(beam line 20) of CSNS. Using water sample, the neutron beam with Φ5 mm exit hole was dispersed related evenly into the forward space. According to the neutron counts of each pixel of the detector module, the readout electronics threshold of each pixel is adjusted. Compared with the unadjusted detector module, the inhomogeneity of the detection efficiency for the adjusted one has been improved from 69% to 90%. The test result of the diffraction peak of the standard sample Si showed that the adjusted detector module works well.

Colorimetric Sensing of Hydrogen Peroxide Based on the Wavelength-Shift of CsPbBr_(3) Perovskite Nanocrystals on Water-Oil Interface

In this study,the halogen exchange reactions are investigated between KI or methylamine iodide in aqueous solution and CsPbBr_(3)NCs in toluene.The mass transfer process on the interface between water and toluene affects the halogen exchange time and e fficiency.Stirring and heating can effectively improve the halogen exchange e fficiency and increases the sensing sensitivity.The photoluminescence wavelength shift of CsPbBr_(3)NCs shows good linear relationship with the concentration of I-in the range from 0 to 20 nmol/L with the detection limit of 0.2 nmol/L I^(-).Taking H_(2)O_(2)as a typical water-soluble oxide,the method is applied to the colorimetric sensing of H_(2)O_(2)in water solution.After the optimization of sensing conditions,the obvious wavelength shift could be observed with the different concentration range of H_(2)O_(2).A good linear relationship between the wavelength shift and the H_(2)O_(2)concentration from 0 to 1.0 mmol/L with the detection limit of 0.05 mmol/L H_(2)O_(2)could be found.

基于光纤光栅的煤层瓦斯钻孔塌孔位置表征试验研究

钻孔瓦斯抽采是解决瓦斯超限问题的重要手段,受地应力、钻进扰动等影响矿井瓦斯抽采钻孔易塌孔变形,严重影响瓦斯治理效果。针对煤层瓦斯抽采钻孔塌孔位置难以监测的问题,提出了一种基于光纤光栅智能传感技术的钻孔塌孔监测技术。首先从光纤光栅传感器应力监测理论出发阐述了光纤光栅钻孔塌孔监测原理,在此基础上构建了基于光纤光栅的塌孔表征实验平台,开展了不同塌落煤量下3种光栅布置方式(0°、90°、180°)的钻孔塌孔监测模拟试验,研究了光栅测量波长偏移量、抽采流量随塌落煤量的变化规律,划分了钻孔塌孔等级。结果表明:光栅测点位于基体材料下方布置方式的塌孔监测准确度最高,此时中心波长偏移量Δλ与塌落煤量m的关系为m=3.017Δλ.抽采流量Q与波长偏移量Δλ的关系为Q=8.72E-7x^(3)+2.30E-4x^(2)-0.18x+30.以抽采流量衰减率为塌孔评判标准划分三级塌孔标准:Ⅰ级塌孔抽采流量衰减至90%,Ⅱ级塌孔抽采流量从90%衰减至50%,Ⅲ级塌孔抽采流量衰减至50%以下。最后,通过在潞安集团漳村煤矿2802工作面的现场试验验证了光纤光栅塌孔监测技术的有效性,发现钻孔30 d后塌孔位置分布与钻孔打钻完成后的初期期情况相近;在现场试验中,基于所提出的塌孔监测技术成功定位并修复了5个钻孔,修复后钻孔瓦斯抽采纯量较未修复前提升了37.79%。

超精密平面光学元件检测技术

超精密光学元件是决定高端装备性能的核心元件,在大科学装置、精密仪器等领域中被广泛应用。对光学元件进行高精度检测是保证元件质量的重要途径。光学检测技术因具有非破坏性、高精度而成为光学元件检测的有效技术。首先,对超精密光学元件主要检测技术进行了综述,重点介绍技术原理、研究现状和应用瓶颈;其次,针对光学检测技术中的相位解调问题,以波长移相测量技术为例,结合超精密平面光学元件检测,概述了相位解调算法的原理与实现过程,并对其性能进行综合评估;最后,展望光学元件检测技术的未来发展趋势。

基于孤子自频移效应的超短脉冲波长连续调谐

作为光纤非线性效应中的一种,孤子自频移效应由于其特殊的脉冲自持性而成为光纤中超短脉冲波长调谐的有效方式。从理论计算和实验验证角度对光纤中的孤子自频移效应进行研究,基于广义非线性薛定谔方程对光纤中的孤子自频移效应进行仿真计算,通过测量超短脉冲在保偏光子晶体光纤输出端的光谱对其进行实验分析,理论和实验结果相符合,均表明基于孤子自频移效应的超短脉冲波长可以实现大于300 nm的光纤反常色散区连续调谐。

光纤光栅传感应用中的波长编码信号解调技术

波长编码信号解调是实现光纤光栅多参量、多点分布式传感网络的核心技术之一。总结了光纤光栅传感信号解调的一般原理和技术难点,分类评述了常用解调方法的工作机理、特点和性能。同时,提出了一种新的闭环反向锁定解调方法,它既具有高波长分辨率(优于2pm)的优点,又有效降低了系统成本。

光纤光栅传感器波长移位检测方法

光纤光栅波长移位检测是光纤光栅传感器的核心技术之一 ,已提出的光纤光栅波长移位检测方法有被动解调法、匹配光栅法、非平衡 Mach- Zehnder干涉仪法、可调谐窄带光源法和激光锁模法等详细介绍了光纤布拉格光栅(FBG)传感器的波长移位检测方法 ,分析了各种检测方法原理。重点讨论了非平衡 M- Z干涉仪法和可调谐窄带光源法 ,并对以上各种方法的优、缺点进行了分析和讨论。

852nm半导体激光器量子阱设计与外延生长

设计并外延生长了具有高温度稳定性的InAlGaAs/AlGaAs应变量子阱激光器,用于解决852nm半导体激光器在高温环境下工作时的波长漂移问题。基于理论模型,计算并模拟对比了InAlGaAs,InGaAsP,InGaAs和GaAs量子阱的增益及其增益峰值波长随温度的漂移,结果显示,采用In0.15Al0.11Ga0.74As作为852nm半导体激光器的量子阱可以使器件同时具有较高的增益峰值和良好的波长温漂稳定性。使用金属有机化合物气相淀积(MOCVD)外延生长了In0.15Al0.11Ga0.74As/Al0.3Ga0.7As有源区,通过反射各向异性谱(RAS)在线监测和PL谱研究了InAlGaAs/AlGaAs界面的外延质量,实验证明了通过降低生长温度和在InAlGaAs/AlGaAs界面处使用中断时间,可以有效抑制In析出,从而获得InAlGaAs/AlGaAs陡峭界面。最后,采用优化后的外延生长条件,研制出了InAlGaAs/AlGaAs应变量子阱激光器。实验测试结果显示,其光谱半高宽为1.1nm,斜率效率为0.64W/A,激射波长随温度漂移为0.256nm/K。理论计算结果与实验测试结果相吻合,证明器件性能满足在高温环境下工作的要求。

温度对光纤光栅反射波长漂移量的影响

设计建立了一套光纤光栅温度传感实验装置 ,研究了温度对光纤光栅反射波长漂移量的影响。分别对升温和降温过程中光纤光栅反射波长进行了测试 ,得到了升温和降温过程每度反射波中心波长平均漂移量 ,分析讨论了波长漂移与温度的变化方向的关系和温度传感响应速度等问题。结果表明 ,光纤光栅温度传感器响应速度很高 ,反射波长漂移量与温度具有比较好的线性关系 ,且与温度的变化方向无关。

双膜式光纤Bragg光栅土压力传感器的研究

采用双膜油腔结构研制了一种双膜式光纤Bragg光栅土压力传感器,偏压试验表明,此土压力传感器有效改善了与土压力传感器接触部分土压力分布不均的问题。在土压力的作用下,一次膜片变形产生的压力经传压油传递给二次膜片,传压杆与等强度悬臂梁刚性连接,二次膜片中心发生的挠度变化推动传压杆,使等强度悬臂梁的自由端发生同样大小的挠度变化。通过检测粘贴于等强度悬臂梁表面中心轴线上的光纤Bragg光栅的波长移位可获得土压力。载荷试验表明,传感器的灵敏度为412.7 pm/MPa,非线性误差为1.97%FS,重复性误差为3.68%FS。

半导体激光器输出波长随工作电流变化的实验研究

以2W连续红外(980nm)半导体激光器(InGaAs)和120mW连续红外(980nm,带制冷器与尾纤)半导体激光器(InGaAsP)为例,测量激光器输出光束的波长随工作电流变化的规律。实验结果表明:工作电流增加,光束波长向长波红移,斜率分别近似为0.374nm/100mA、0.220nm/10mA;工作电流大时的红移现象比电流小时明显。

曲率半径的高精度测量及其不确定度

为了高精度测量光学元件的曲率半径,提出了一种利用反射式计算全息元件结合波长移相干涉测长技术测量光学球面曲率半径的方法。测试中,将反射式计算全息元件作为基准来标定所用标准镜头参考面的曲率半径,利用波长移相干涉技术测量干涉腔腔长,通过计算分析得到被测元件的曲率半径。文中描述了该方法的系统构成及其工作原理。结合实例,运用理论分析与软件仿真模拟分析了方法的测量不确定度。最后,利用实验室现有的商用波长移相干涉仪进行了实验验证。对一口径为100mm的球面样品进行曲率半径的测量,得到的结果为157.108 3mm;利用接触式球径仪法对同一样品进行对比测量,结果显示相对误差小于0.02%。与其它目前已有的非接触式曲率半径测量方法相比,提出的方法具有误差源少、测量精度高、易于操作等优点。