一种用于滑坡监测的复合光纤装置

针对滑坡体深部位移这一重要指标,基于光时域反射技术,设计了一种蝴蝶结形式的复合光纤装置用于监测深部剪切位移.该传感装置由方形聚氯乙烯树脂管、毛细钢管、光纤、砂浆组合而成.首先在40mm×40mm×500mm(厚2.0mm)的聚氯乙烯树脂方管四周开挖导槽,将Φ1×500mm毛细钢管放置在导槽中.然后用光纤穿入毛细钢管,光纤一端固定,另一端绕制成蝴蝶结形式.最后在聚氯乙烯树脂管外围浇筑Φ110mm的砂浆,制作成圆柱式复合光纤装置.室内边坡模型剪切测试台测试结果表明:该装置对深部剪切位移初测准确度为1mm,最大测量范围为40mm.分析表明该复合光纤装置具有灵敏度高、测量范围大、结构简单易于安装等优点,可以用于滑坡以及野外岩土结构工程等进行现场原位监测.     

基于光纤马赫-曾德尔干涉仪的强度测量研究

根据光外差检测原理，分析得到干涉测量适用于信号光强小于参考光强的探测，直接测量适用于信号光强大于参考光强的探测的结论。利用自制的全光纤马赫-曾德尔干涉仪系统，对位移信号进行了测量。实验结果表明：当位移信号较小时，干涉测量的灵敏度分别为62．068μW／mm和9．90mV／mm，而非干涉测量的灵敏度分别为4．30μW／mm和0．35mV／mm；当位移信号较大时，干涉测量的灵敏度分别为2．643mV／mm和0．055mV／mm，非干涉测量的灵敏度分别为12．326mV／mm和4．194mV／mm，测量结果与分析得到的结论一致。对于光纤干涉仪强度调制检测的应用具有参考价值。     

用于光纤传像束的折-衍混合光学耦接器研究

在光学耦接器设计中引入衍射面，根据衍射光学元件的三级像差理论，分析了衍射面初始结构参量的求解规律，通过理论计算和ZEMAX光学软件的优化，给出工作波长0.4~0.7 μm，焦距27.5 mm，光学长度为64 mm，采用一个衍射面的耦接器设计实例.该耦接器适用于单丝直径16 μm，截面直径为6 mm的光纤传像束.对设计结果的分析表明，折-衍混合耦接器不仅在光学性能方面优于传统的光学耦接器，而且在尺寸和重量上有非常显著的减少.     

FTTH用微结构光纤的性能研究

光纤到户对光纤在小弯曲半径条件下的衰减特性提出了更高的要求。微结构光纤可以实现极小弯曲半径的低衰减光信号传输,是小弯曲半径单模光纤技术解决方案的有力竞争者。设计了一种新的微结构光纤,并研制出光纤样品。这种结构的光纤具有非常优良的弯曲特性。其最小弯曲半径可达2mm,1 550nm附加损耗小于0.1dB,并且具有优良的偏振模色散特性,熔接损耗也非常小,其与G.652D单模光纤的熔接损耗为0.12dB。这些特性使其在光纤到户的复杂应用环境中具有明显的应用优势。     

全光纤低相干光纤位移传感技术

提出并演示了一种由两光纤构成的杨氏干涉解调系统的全光纤低相干光纤位移传感器系统。该技术从根本上避免了光源频率、光强的波动，及光在传输过程中由系统带来的损耗、光的偏振方向的改变引起的信号衰落问题。其结构简单，易于调整，测量分辨率可达０．０５４ｍｍ。     

传像光纤束单丝芯径大小对光纤像面全息图的影响

光纤像面全息可以获得较高衍射效率的全息图和再现较大的物像。文中分析了相干光激励下传像光纤束单丝芯径的大小对其输出光场的影响，以及输出光场中低阶模与高阶模对全息照相的不同作用，在此基础上，提出缩小传像束单丝芯径，增多单丝根数，可以提高光纤像面全息图衍射效率和分辨率的观点，并通过实验进行了验证。     

基于非本征Fabry-Perot腔光纤液位传感器研究

介绍了适用于液位测量的强度型非本征法布里-珀罗（F-P）腔光纤液位传感器的结构设计及其性能.实验观察到F-P腔具有良好的多周期输出特性和局部的线性特性,选用局部的1/4周期输出线性段作为线性工作区间可对液位进行高准确度、连续性测量.恰当选择敏感组件的尺寸可设计不同量程的传感器.实验结果表明,传感器测量3.5 m水位时,精确度为±2 mm,最小分辨率为1 mm.     

非均匀光纤光栅响应特性的研究

光纤栅在未来光纤通信与光纤传感系统中将关键性作用。本文进行了不同线型光栅迹与喃啾 等波导结构参数下的非均匀光纤光栅响应特性的数值计算,并通过对光栅响应不对称性的研究讨论,提出了光栅响应对称性的两个一般条件。     

光外差干涉全光纤表面粗糙度传感器的研究

本文介绍了基于半导体激光器线性调频干涉技术的全光纤表面粗糙度传感器的研究，该传感器的灵敏度为０．００５μｍ，量程为４ｍｍ，属微型化传感器，辅之以机械传动机构可完成对复杂曲面表面，沟槽表面及３ｍｍ以上内孔表面的表面粗糙度测量，且结构简单易于实用化。     

Strained Chirped Fiber Bragg Gratings Based all-fiber Variable Optical Delay Line for Optical Coherence Tomography

We present the novel all-fiber optical delay line that can be realized by exploiting the fundamental distributive reflection characteristics of a chirped fiber Bragg gratings (CFBG). With the assist of a strained CFBG and a designed fiber stretcher, the proposed delay line could perform the function (such as attainment of variable large enough optical delay without dispersion mismatch) of the conventional optical delay line within the optical fiber. While the strained CFBG produced 3.1 mm optical delay, the pair of CFBGs in the opposite direction can manage dispersion imbalance of the delay line. The use of the PZT-based fiber stretcher can enable depth scanning at a high repetition rate for real-time imaging. The performance of the delay element is demonstrated with measured experimental results. OCT system embedded with the all-fiber variable optical delay line showed the axial resolution of 100 μm and the dynamic range of 50 dB. The implemented system was used for the imaging of a biomedical sample, which proves the utility of the proposed delay element as a promising alternative of optical delay line.     

光锥的光学传递函数测试方法研究

从传像方式上给出了光锥的理论传递函数,并提出了利用星点像分析测试其MTF的方法,通过具体实验给出了MTF的测试结果.测试结果表明,合理的选取测试组件参数,可以得到光锥在较大频率范围内的光学传递函数(>100 lp/mm) .从MTF趋势上看,测试结果与理论推导呈一致性.     

偏芯光纤弯曲特性分析

根据光纤传输理论建立了偏芯光纤理论计算模型.采用保角变换方法将偏芯光纤不对称的三层结构转换成同轴对称的三层结构,得到关于传播常量的特征方程,给出了偏芯光纤弯曲损耗公式.仿真分析了偏芯光纤弯曲损耗和弯曲半径之间的关系,结果表明当弯曲半径达到3mm时,弯曲损耗几乎为零,同时得到弯曲损耗随偏芯距离的变化关系.运用Rsoft软件中的BeamPROP模块建立偏芯光纤弯曲的光学模型,模拟仿真了弯曲的偏芯光纤中模场分布情况.仿真结果表明,偏芯光纤的弯曲方向与纤芯偏移中心轴线方向相同的弯曲损耗小于反方向的弯曲损耗.     

非线性光纤环：2.掺铒光纤全纤光学双稳态实验

利用掺饵光纤和光纤定向耦合器组成全光纤谐振腔，在光学非线性条件下，实现了全纤光学双稳运转，实验双稳阈值与理论相符。     

非线性光纤环:3.掺铒光纤双稳态数字光信号放大器

讨论了各种掺铒光纤双稳全光信号放大器的原理和特性，计算了它们在恒定光偏置和脉冲光偏置下的光增益及其随器件参数的变化，给出了器件的设计原则。     

Luminescence-Based Optical Fiber Chemical Sensors

A scheme for the simultaneous determination of temperature and analyte concentration for application in luminescence-based chemical sensors is proposed. This scheme is applied to an optical oxygen sensor, which is based on the quenching of the fluorescence of a ruthenium complex. Temperature measurement is performed using the excitation radiation and an absorption long-pass filter. Preliminary results are presented that show the viability of an oxygen measurement that is independent of temperature and optical power level. The possibility of self-referenced temperature measurements with semiconductor nanoparticles is also investigated. In order to optimize the sensor design, several different optical fiber probe geometries for oxygen sensing are tested and compared, including different methods of coupling radiation into the optical fiber system. Polyvinyl alcohol (PVA) and polyacrylamide membranes are tested as supports for sensor immobilization in fiber-optical pH sensing devices in aqueous solution. Some results are presented that show the feasibility of using fiber-optical pH indicators for remote monitoring.     

Luminescence-Based Optical Fiber Chemical Sensors

Abstract

A scheme for the simultaneous determination of temperature and analyte concentration for application in luminescence-based chemical sensors is proposed. This scheme is applied to an optical oxygen sensor, which is based on the quenching of the fluorescence of a ruthenium complex. Temperature measurement is performed using the excitation radiation and an absorption long-pass filter. Preliminary results are presented that show the viability of an oxygen measurement that is independent of temperature and optical power level. The possibility of self-referenced temperature measurements with semiconductor nanoparticles is also investigated. In order to optimize the sensor design, several different optical fiber probe geometries for oxygen sensing are tested and compared, including different methods of coupling radiation into the optical fiber system. Polyvinyl alcohol (PVA) and polyacrylamide membranes are tested as supports for sensor immobilization in fiber-optical pH sensing devices in aqueous solution. Some results are presented that show the feasibility of using fiber-optical pH indicators for remote monitoring.     

超细低水峰抗弯损光纤的设计及制作

采用全合成预制棒制造法（VAD＋OVD）和改进的G.652.D光纤拉制法制造光纤.研究了工艺中光纤芯径的大小、第一包层的厚度、芯包折射率差、芯包比等参量与光纤弯曲性能的关系,并据此制作了几种超细低水峰抗弯损光纤.该光纤的裸光纤直径约80 μm,涂覆后成品光纤直径约140 μm,当弯曲半径不小于7.5 mm时,能够在1 260～1 625 nm整个波段内满足DWMD的传输要求.     

光纤激光器及其在传感中的应用

介绍了光纤激光器的基本结构和特点，着重介绍了光纤激光器在相位型、波长型、光强型和偏振态型传感器中的应用，指出了光纤激光器在传感中的发展趋势。     

长距离光纤布里渊散射研究

研究了25 km长距离光纤中布里渊散射的功率分布,提出了求解长距离光纤中布里渊散射的耦合强度方程的数值计算方法,与忽略光纤损耗的解析解进行比较,并从实验上加以研究.在此基础上,分析了25 km长距离光纤中布里渊散射过程,得到泵浦波和斯托克斯波沿光纤的功率分布图.     

Infrared Optical Fiber Sensors

Notably improved performance as well as extended application areas is expected in the technology of optical fiber sensors using infrared fibers that transmit radiation in a wavelength range beyond 2 μm. Measurement of infrared radiation is particularly important in thermometry and spectrometry. In these areas, the use of infrared fibers has been studied extensively not only as a transmission waveguide but also as a sensor chip. Of various infrared fibers, fluoride glass fibers exhibit the lowest transmission loss and hence are useful for remote sensing that requires light transmission over a long distance. The wide transmission range of chalcogenide glass fibers and halide crystalline fibers is valuable for thermometry in a low temperature range and for spectrometry of various molecules. Hollow waveguides are useful as a capillary flow cell that realizes fast-response spectrometry. The advantages and disadvantages of infrared fibers must be considered carefully in the development of fiber sensors. In this paper, the progress of infrared optical fiber sensors is reviewed with particular interest in thermometry and spectroscopy.