利用磁光玻璃光纤测大电流的光纤电流传感器的设计

介绍利用磁光玻璃法拉第效应测量大电流的方法,选用ZF1磁光玻璃直接拉锥成光纤作为传感器的探头,利用保偏光纤作为传导光路介质,根据法拉第效应,偏振光在磁场中偏振面的改变角α＝V·D·B,V和D为已知,可得磁感应强度B,再利用通电直导线电流与它周围磁场的关系可测得大电流。     

法拉第磁光波导的耦合模分析

利用法拉第磁光效应可以设计光纤磁场传感器。在磁场传感过程中，磁光晶体薄膜波导的TE模和TM模式之间将发生转换，：其转换效率与磁光晶体的法拉第旋转角度和双折射有关。本文建立了磁光波导的耦合模方程，分析了磁光波导中的TE—TM模转换，提出了通过减小线性双折射和增大法拉第旋转角来提高TE—TM模耦合效率的措施，这些措施有利于增大光束TM模的输出功率并提高光纤磁场传感器的灵敏度。     

低价磁光材料呈现不对称法拉第效应

据密尔沃基马克特大学研究人员说，一块低价丙烯酸可用作为光调制器、光传感器或磁传感器，或测定光束的传播方向。这种器件的原理——磁光效应或法拉第旋转——并不是新发现的。但马克特大学电气工程系的Joong-Kil Kwon等人还首次观察到一种不对称的法拉第旋转，这就是说，当光束在磁场中沿两个相反的方向传播时，其偏振角的旋转不一样。     

高灵敏度温度稳定BiGd：YIG磁光光纤电流传感器 性能及其晶体生长研究

法拉第磁光光纤电流传感器因其具有结构简单、安全可靠、高精度和灵敏度等优点而受到国内外的广泛关注。法拉第传感材料的磁光性能对于光纤电流传感器的性能有重要的影响。本文用熔盐法生长了高法拉第旋转角、温度稳定的稀土铁石榴石磁光单晶BiGdYIG,测试分析了其在近红外波段的磁光性能及其温度特性。其法拉第旋转角θ     

精细表面下细小缺陷的磁光涡流成像实时探测

磁光涡流成像检测装置可实现精细表面下细小缺陷探测。在该装置中，通过物体表面上方的交流激励线圈实现传统的涡流感应，涡流所感应的磁场由法拉第效应来检测。为了实现表面下缺陷的检测目标，激光穿过安放在激励线圈中的特殊的磁光晶体，激光偏振方向在晶体中的旋转大小取决于检测区域磁场的大小，缺陷将使检测区域磁场分量发生变化并使偏振光的旋转角发生相应变化，通过一光学装置转化成“明”或“暗”图像，该光学装置由传统的显微镜、照明系统、偏振器和CCD图像传感器组成。给出了初步的实验探测结果。     

高灵敏度温度稳定BiGd：YIG磁光光纤电流传感器性能及其晶体生？…

法拉第磁光光纤电流传感器因其具有结构简单,安全可靠、高精度和灵敏度等优点而受到国内外的广泛关注。法拉第传感材料的磁光性能对于光纤电流传感器的性能有重要的影响。本文用熔盐法生长了高法拉第旋转角、温度稳定的稀土铁石榴石磁光单晶ＢｉＧｄ：ＹＩＧ,测试分析了其在近红外波段的磁光性能及其温度特性。     

基于法拉第旋光效应的葡萄糖浓度传感研究

本文主要研究葡萄糖、葡萄糖氧化酶(GOD)以及 两者的混合溶液的法拉第磁致旋光效 应,为基于法拉第旋光效应的葡萄糖传感器提供了理论依据,研究介质的旋光特性,可以更 好地提升光电传感器的性能,更广泛地应用光电传感器。在法拉第磁致旋光效应中,当介质 处于磁场中时,平面偏振光透过该介质时,偏振面会旋转一个角度。将不同浓度的溶液置于 磁场中,使用532 nm的激光器,激光通过起偏器光变成了平面偏振光 ,使平面偏振光透过溶 液和检偏器,记录通过检偏器的光强并根据马吕斯定律计算旋光角。实验发现,随着磁感应 强度的增加,旋光角与磁感应强度呈线性增加关系;随着溶液浓度的增加,溶液的旋光角也 随之增加,磁场对低浓度溶液的旋光角影响更大。可以建立线性关系表示浓度和旋光角的关 系。     

用于金属电解的光纤电流传感器

介绍了ABB瑞士有限公司联合研究中心的科研人员研制的用于高达500kA直流的一种高精度光纤电流传感器。其应用包括对铝、铜、锌和镁等金属生产的电解工艺进行控制。与现代化的霍尔效应基电流转换器相比,该传感器在性能和使用便利性方面均具有明显的优势。该传感器利用了载流母线周围光纤环中的法拉第效应。采用偏振旋转反射干涉仪和光纤陀螺仪技术的新方案来测量磁一光相移。已开发出一种将传感光纤封装在一根柔软的纤维增强环氧带中,以使光纤环直径达数米的适当的技术。在宽的电流和温度范围内,该传感器的精度和重复性均很好,在±0．1％以内。不管给定的磁场分布如何,传感器的校准都是有效的,并且在反复使用柔软敏感带的情况下仍然保持稳定。     

光偏振的微小旋转角的测量技术

本实验提供一种对光偏振的微小旋转角的测量技术、实验采用法拉第调制方法,分别用６３２．８ｎｍ的Ｈｅ－Ｎｅ激光器和５３２ｎｍ的ＬＤ泵浦固体激光器做测量光源,对乙醇水溶液（浓度５０％）的磁光法拉第偏振角进行测量,当改变外加磁场的磁感应哟度时,可使偏转角在亚毫度范围内取值,采用这一技术,对蔗糖水溶液的旋光角进行测量,浓度低达每毫升１０＾４克,为具有小的常德常数的化学物质或生命物质地旋光测量提供了很好的手段     

高灵敏度的光磁式电流传感器

介绍了结构上带气隙的园环铁芯,采用新型传感元件设计的法拉第效应光磁式电流传感器.该传感器元件是一块经过精细研磨的玻璃棱镜,棱镜的两端面有高反射能力的镀层,经棱镜传播的光束在玻璃/空气界面上会进行20次的临界反射.新设计的电流传感器,其灵敏度比基于类似原理的原设计产品几乎高3倍.     

Sensitivity improvement of an optical current sensor with enhancedFaraday rotation

A sensitivity improvement technique is proposed for a class of bulk-glass optical current sensors that employ a ferromagnetic field concentrator. The total effective optical path length is demonstrated theoretically to be an invariant regardless of the bulk glass thickness and consequently independent of the size of the concentrator gap opening. Thus, if the magnetic field is increased by reducing the gap size, the eventual Faraday rotation for a given electric current can be increased proportionally, leading to an improved device sensitivity. The dependence of the gap magnetic field on gap size is calculated with an equivalent circuit model, and this analytical treatment is compared with a dedicated finite element computer package. By taking account of various types of optical power losses present in the bulk glass, the above formulated gap dependence of magnetic field is used to aid a realistic assessment of device sensitivity and this serves as a tool to design and analyze practical bulk-glass optical current sensors. A detailed experimental study to confirm the proposed sensitivity improvement technique is also reported     

全光纤口腔OCT系统偏振波动自动消除方法研究

采用法拉第旋转效应自动消除伞光纤口腔光学相十层析(OCT)成像系统巾光纤Miehelson干涉仪干涉臂单模光纤中随机偏振态变化对十涉信号的影响,使得无论样品臂和参考臂光纤中光偏振态如何发生变化,干涉信号始终保持最强.介绍了该方法的基本原理、获得了离体牙齿稳定十涉信号和二维OCT图像.     

双光路全光纤电流互感器的研究

为了使光纤电流互感器具有快速、准确地测量出电流值的能力,本文在分析法拉第电磁感应效应的偏振调制型全光纤电流互感器的基础上引入双光路检测法,将光纤中输出的线偏振光分成振动方向相互垂直、传播方向成一定夹角的两束光。经光信号转换器转换成电信号后系统对其进行放大、滤波处理后得到无噪正弦波信号,结合TMS320F28335测试平台对输出的两路信号进行同步采集、解调,通过运算求出法拉第旋转角,并拟合法拉第旋角与参考电流值得出两者关系式,最终使测量系统能够在高压环境下快速、准确地测量电流值。由此可见,本系统适用于高压环境下对大电流进行检测。     

Novel Bi-substituted Yttrium Iron Garnet Film／Crystal Composite for Magneto-optical Applications

The novel Bi-substituted rare-earth iron garnet films were grown by the modified liquid phase epitaxy (LPE) technique for use as a 45° Faraday rotator in optical isolators. First, single crystals of Y3 Fe5 O12(YIG), with a lattice constant of 1. 237 8 nm, were grown by means of the Czochralski method. Using the seed crystal of YIG instead of the conventional non-magnetic garnet of Gd3Ga5O12 (GGG) as a substrate,a film of BiYbIG was grown by means of the LPE method from Bi2O3 - B2O3 fluxes. The structural, magnetic and magneto-optical properties of BiYbIG LPE film/YIG crystal composite have been investigated using directional X-ray diffraction (XRD), electron probe microanalysis (EPMA), vibrating sample magnetometer (VMS) and near-infrared transmission spectrometry. The saturation magnetization 4πMs has been estimated to be about 1.2×10 6 A/m. The Faraday rotation spectrum was measured by the method of rotating analyzer ellipsometry (RAE) with the wavelength varied from 800 nm to 1 700 nm. The resultant Bi0.37 Yb2.63 Fe5 O12LPE film/YIG crystal composite showed an increased Faraday rotation coefficient due to doping Bi3 ions into the dodecahedral sites of the magnetic garnet without increasing absorption loss, therefore a good magnetooptic figure of merit,defined by the ratio of Faraday rotation and optical absorption loss, has been achieved of 21.5 and 30.2 (°)/dB at 1 300 and 1 550 nm wavelengths respectively and room temperature. Since Yb3 and Y3 ions provide the opposite contribution to the wideband and temperature characteristics of Faraday rotation,the values of Faraday rotation wavelength and temperature coefficients were reduced to 0.06 %/nm and 0.007(°)/℃ at 1 550 nm wavelength, respectively.     

Faraday效应对空间目标探测雷达的影响

分析了电离层Faraday旋转效应对空间目标探测雷达的影响。从磁离子理论出发,结合电离层模型和地球磁场模型,使用了一种快速的Faraday旋转角计算模型,并与传统使用的经验计算方法进行了比较,表明该方法普适性强,更适用于中国地区。针对当前国际上典型的空间目标探测雷达工作频段,选取我国海口（低纬地区）和长春（中纬地区）为代表,分别计算了太阳活动极大年和极小年间的Faraday旋转角,给出了仿真结果并进行分析,表明Faraday旋转效应给线极化方式雷达带来明显的回波能量损失。在进行雷达设计时,需要将该效应与雷达系统性能综合考虑,采用合适的天线极化方式。     

8C1--The laser current transformer for EHV power transmission lines

A current measuring device applicable to an extra-high voltage power transmission line higher than 500 kV is proposed with preliminary experimental results. It obtains the instantaneous magnetic field ajacent to a transmission wire by measuring the angle of Faraday rotation of a laser beam in a flint glass rod. The laser beam is transmitted and analyzed at a ground potential site, and in the energized part this device has neither insulated conductors nor active elements. An experimental laser current transformer yielded a sensitivity of 66 mV per 100 A and good linearity. Various sources of error and modifications are discussed.     

一种新型偏振相关磁光隔离器的设计

该文介绍了一种新型的光纤型法拉第磁光隔离器设计方法,利用液相外延制备的单晶石榴石(BiTm)3(GaFe)5O12膜作为法拉第转子,通过对光路结构的改进设计,有效降低了光隔离器体积和所需饱和外场。当外磁场H=47×103 A/m时,法拉第旋角可达到45°@1 550 nm,光吸收系数为15 cm-1 @1 550 nm,光透射率为85%@1 550 nm,整体满足设计要求。     

Magneto-Optical Properties of Wider Gap Semiconductors ZnMnTe and ZnMnSe Films Prepared by MBE

The II-VI based magnetic semiconductors with a direct and wide optical bandgap are expected to show high potential for optical applications utilizing short wavelength laser diodes (LDs), such as 532-nm green and 475-nm blue LDs. We have confirmed that the Faraday rotation θ_F in the ZnMnTe and ZnMnSe films deposited on quartz glass (QG) and sapphire (SA) substrates by using molecular beam epitaxy (MBE) is large near the absorption edge. This paper reports the magneto-optical properties of ZnMnTe and ZnMnSe films synthesized on the QG and SA substrates, and shows the result of a direct Faraday rotation observation successfully made for the ZnMnTe films under 1.28-kHz alternating magnetic fields. The optical absorption characteristics of the ZnMnTe films grown on the SA substrates by MBE are discussed by comparing them with the optical absorption properties and photoluminescence spectra of the II-VI ZnTe parent single crystals.     

HCN激光偏振干涉测量等离子体极向磁场

介绍了一种利用HCN激光器测量等离子体极向磁场的诊断方法。设计建造了一台偏振干涉仪 ,获得了测量精度为 0 3°的法拉第旋转角。实验结果显示该系统可用于HL 1M托卡马克的极向场测量。