Relationship between rheological manufacturing process and optical performance of optical fiber coupler

Through theoretical analysis and experiments, the viscoelastic mechanical model of optical fiber coupler in the process of fused biconical taper was established, and the numerical analysis in non-uniform temperature field was made. The results show that the rheological parameters, such as drawing speed and fused temperature, have a tremendous influence on stress distribution and performance of optical fiber coupler, especially the influence of fused temperature. The change of fused temperature by 5 ℃ can lead to the change of the maximum stress by 30% and stress difference by 20% in the same cross section. The change of temperature gradient by 3% can result in the change of stress difference by 90%. In the present condition of rheological technology, rheological defects such as crystallizations and microcracks are easy to generate in the optical fiber coupler.     

Effect of technological parameters on optical performance of fiber coupler

To find out the influence of technological parameters on optical performance of fused optical fiber device, the fiber coupler was served as subject investigated by using the fused biconical taper machining as experimental setup. Fused fiber coupler＇s optical performances such as insertion loss, excess loss, directivity and uniformity were tested with the optical test system that was constituted of tunable laser and optical spectrum analyzer. Especially the relationship between optical performance and drawing speed was investigated. The experimental results show that the optical performance is closely related to process conditions. At fused temperature of 1 200℃, there exists a drawing speed of 150μm/s, which makes the device＇s performance optimum. Out of this speed region, the optical performance drops quickly. At drawing speed of 200μm/s, the excess loss is relatively small when the fused temperature is above 1 200 ℃. So the technological parameters have close relationship with optical performance of the coupler, and the good performance coupler can＇t get until the drawing speed and fused temperature match accurately.     

Structure analysis of optical fiber coupler with infrared spectrometry

To obtain excellent performance optical fiber couplers, the structural difference of SiO2 in couplers with different manufacturing techniques was investigated. With 740-FT-IR infrared spectrometric analyzer, the infrared absorption spectrum of SiO2 in couplers at different drawing velocities was measured, and two characteristic peaks in the wavenumber range of 650 - 2000 cm^-1 were observed. One characteristic peak is at about 943 cm^-1 , which is attributed to Si--O Si bond asymmetric stretching vibration, the other is at about 773 cm^-1 , which is attributed to Si--O--Si bond symmetric stretching vibration. From the infrared spectrum, it is found that the intensity and wavenumber of the characteristic peaks are related to the manufacturing technique of couplers. The characteristic peak atabout 943 cm^-1 becomes steeper when increasing the drawing velocity. At the drawing velocity of 150μm/s, the distance between the two characteristic peaks is maximum, and then the optical fiber coupler has excellent performance, indicating that the performance of the optical fiber coupler has a close relationship with the wavenumber of the two characteristic peaks.     

熔融拉锥型光纤耦合器损耗的实验研究

结合2×2熔锥型光纤耦合器的制作,实验研究了拉锥速度、耦合长度、火焰位置3个关键制作参数对耦合器的插入损耗和附加损耗影响。当拉锥速度控制在150μm/s时,耦合器的插入损耗和附加损耗可以控制在较低水平;在拉锥长度较短的区间内,插入损耗与拉锥长度基本成线性关系;制作低损耗耦合器,火焰存在最佳高度为5.75 mm。     

Novel manufacturing method of optical fiber coupler

Based on the coupling mode theory that the coupling ratio of fiber coupler changes periodically with center distance of two optical fibers, a novel manufacturing method of optical fiber couplers was developed with fused biconical taper experimental system. Its fabrication process is that the fiber is fused but not stretched when light begins to split, and the reduction of diameter of fiber is dependent on the theological characteristic of the fused fiberglass. The performance of the coupler was tested. The results show that the performance of the novel optical fiber coupler meets the performance expectations, and its diameter of coupling region （about 30 μm） is twice as long as that of classical fused biconical taper coupler （about 16 μm）, so the default, that is, the device is easy to fracture, is restrained and the reliability is greatly improved.     

光纤锥探针传输特性的研究

采用局域模式耦合理论 ,对两类光纤锥探针———腐蚀锥和熔拉锥的传输特性进行了比较和分析 ,得出了光在探针锥中传输时耦合效率的分布情况 ,以及传输效率随锥长、针尖直径和光波长变化的特性 .     

特种光纤参数检测及承载性能分析

对自制特种液芯光纤进行了几何参数（直径）的检测，提出了一种基于数字图像处理的高效、实用的分析方法来测量光纤的直径.通过承载性能实验，测试了石英光纤、塑料光纤和特种液芯光纤的承载性能.结果表明，液芯光纤对外界的承载变化比较敏感，有较好的光强传感性能，具有和普通光纤相似的性质.根据液芯光纤输出光强的变化，可以判断其承载的大小，其承载能力比石英光纤和塑料光纤好.     

布拉格光栅辅助型上下话路滤波器的实验制作

采用波长为248nm的紫外光,在由标准单模光纤和自制的高掺锗光敏光纤熔融拉锥制作的2×2光纤失配耦合器上写入光纤光栅,实现了全光纤布拉格光栅(FBG)辅助失配耦合器型上下话路滤波器,并测试了器件的传输特性,器件的插入损耗和回波损耗分别为6.74dB和-18.84dB。用10Gbps的光信号进行了传输实验,分别测试了下话路前、后信号的眼图。与输入信号相比,下话路信号的信噪比从10.04dB降低到了9.27dB,信号的消光比从8.89dB降低到了4.68dB。     

置入光纤传感器测定FRP残余应力的研究

利用最新发展的基于光纤微弯传感原理制作的缠绕式光纤应变传感器来测定FRP的残余应力.自行设计模具以制成两种FRP复合材料试件,一种为按照普通成型的过程制成试件,另一种为采用预加张力复合原理制成试件,通过测量两种试件的残余应力,得到大量有价值的实验数据,分析、对比实验结果,得到预加张力引起的残余应力.说明给纤维预加张力后,能提高复合材料的强度水平,对获取高质量的复合材料产品具有重大意义.     

光纤熔融拉锥中拉力控制方法与电磁力仿真

针对保偏光纤耦合器熔融拉锥制造过程中拉力控制问题,提出一种新的计算机在线拉力控制方法.拉力控制系统由计算机、拉伸机构、圆光栅及控制电路组成,通过检测光纤支架的旋转角度、改变线圈中的电流,控制永磁铁与线圈间的电磁力,实现对拉伸力的实时控制.分析电磁力和拉力的关系,建立永磁铁和线圈的三维有限元模型,确定永磁铁的运动轨迹,并对通电线圈的磁场分布和电磁力进行仿真,得到线圈中的电流、支架旋转角度和拉力的关系式.仿真结果表明拉力控制良好,控制误差约为1.03%.     

同时测量折射率和温度的光纤传感器

为了实现折射率（RI）和温度的同时测量, 提出了一种双长周期光纤光栅(LPG)结构的光纤传感器. 该传感器由两段LPG组成, 两段LPG所激发的包层模阶数不同, 且两段LPG的包层直径也不同. 理论分析了该传感器实现折射率和温度同时测量的原理, 两段LPG对折射率具有较大差异的灵敏度, 而温度灵敏度也略有不同, 利用灵敏度矩阵可以同时得到折射率和温度的变化. 实验中, 采用两个不同的周期使得两个LPG分别激发不同阶的包层模, 利用化学腐蚀方法使激发高阶模的LPG包层直径减小, 利用不同折射率的液体作为样本进行实验测量. 实验结果表明, 该传感器能实现折射率和温度的同时测量, 并具有高灵敏度和好的线性度.     

一种新型反射式光纤压力传感器的设计分析

将应变式压力传感器的弹性膜片与一种光纤位移检测装置相结合构成了一种反应式光纤压力传感器,阐述了其设计思想,并给出了一个设计实例。该互补偿型传感器可以消除环境温度、光源输出功率波动及光路损耗变化等因素的影响。     

分布式光纤测温技术性能分析

光纤传感器可构成传感网络,实现分布式测量,广泛应用于大型建筑物的结构健康监测等方面,因此分布式光纤传感技术成为近年来光纤传感领域的研究热点.文章通过分布式光纤测温系统的工作原理、特点及性能等方面,从基于光纤后向散射的光时域及频域反射技术的分布式光纤测温和基于光复用技术的光纤光栅分布式测温的分布式光纤测温技术两个研究方向进行了综述;同时阐述分析了两个方向在建筑节能测温中的应用情况,并提出了展望.     

自适应弹性环光缓存结构设计及其网络性能分析

最大缓存时间限制、时延粒度限制、光分组长度限制3大限制因素,对传统光缓存器的前馈型和反馈型两种结构进行了分析。分析表明,影响光缓存器性能的3大限制因素在两种结构中的相互制约关系限制了光缓存器性能的进一步提高。在此基础上提出的一种自适应弹性环光缓存器(E-FLOB)结合了两种传统结构的优势,并分离了3大限制因素间的相互制约关系。结构分析显示,E-FLOB在缓存级数为16时可减少反馈型光缓存器噪声积累约3个数量级。网络性能仿真表明,弹性环结构比前馈型结构使用更少的缓存级数,获得比两种传统结构更低的分组丢失率。     

The Characteristics and Application of Polymer Optical Fiber

1　IntroductionWiththerapiddevelopmentofinformationtechnolo gy ,theneedsandthecapabilityofcommunicationarein creasedquickly .Inordertosatisfytheneedsthehighde velopmentofdatacommunicationandnetwork ,thetrans missionmediahastopossessahighcapability .Themono modelquartzopticalfiberhasgoodpropertiessuchaslowlossandwidebands ,soitplaysamainroleinthecom municationnetwork .Inourcountry ,opticalfiberwillde velopinthelocaldomainnetworkandjunctionnetworkandwillbepossibletoendusers ,butitscostblocksthed…     

光纤激光器的发展与应用

本文对光纤激光器的现状、发展和应用进行了综述。光纤激光器从掺杂稀土元素发展到掺杂过渡族金属元素;掺杂方法从单纯化学气相沉积（Chemical VaporDeposition,CVD）发展到气相、液相、溶胶-凝胶（sol-gel）和改进的化学沉积（MCVD）等;光纤结构从单包层、双包层到今天的多芯双包层光子晶体光纤;激光功率已经到几十千瓦,光子晶体光纤激光器的功率也已超过1.5 kW。目前,它们广泛应用于造船、航天、机械、电器、汽车、化工等多个领域。新光纤技术的成功,必将推动多种产业的快速发展。     

测量微振动的光纤Sagnac干涉传感器

提出了一种光纤Sagnac干涉传感器,用于固体表面传播的超声波产生的微弱振动检测.当超声波信号在固体中传播并作用于光纤传感器的敏感环时,干涉仪的输出光强度受到了超声信号的调制;通过检测干涉仪的输出光强度并利用Fourier变换,获得了超声信号的频率特征.对传感系统的相位调制特性进行了仿真,并对实验结果进行了分析,结果表明该系统可用于固体中传播的超声波的频率特征识别.     

大量程分布式光纤传感器的研究与应用

采用线型和螺旋型光纤传感技术相结合的方法研制出大量程、高定位精度的分布式光纤位移传感器,并对其量程扩展技术和埋设工艺进行了探讨。研究表明,研制的分布式光纤传感器水平位移监测的动态范围达到17 mm,深度定位精度为±0.2 m,可根据需求进行量程扩展,非常适合用于滑坡体深部变形的安全监测。     

低相干光干涉法测量光子晶体光纤延时

对相位敏感型低相干光干涉(OLCR)法延时测量系统进行了理论分析,建立了相关数学模型,搭建了基于非平衡迈克尔逊干涉仪的OLCR测量装置,以掺铒光纤放大器(EDFA)自发宽谱光作光源,对光子晶体光纤(PCF)延时(1540～1560nm)进行测量,取得0.14ps左右的测量精度。利用该系统测量光学元件参数,多采用元件末端面反射光与参考光干涉,但对光纤等器件的延时参数进行测量时,利用透射光会更加方便。     

光纤微弯传感器结构及其性能研究

本文对各种不同结构的光纤微弯传感器进行了深入分析。并按这类光纤传惑器各组成部份的作用和结构特点,分为光纤传感体、光纤微弯器和弹性变形体三个部分。进一步对几种不同结构的光纤微弯传感器进行了传感性能试验和研究,并总结出了它们的传感规律。这对光纤微弯传惑器的进一步发展和应用,提供了有价值的资料。