多参量同时测量的干涉型光纤传感器

提出用椭圆纤芯高双折射光纤偏振干涉和双模干涉结合的四参量以及双模干涉的多参量同时测量的传感理论和实验原理，对交叉灵敏度作了分析，同时给出了误差分析，并结合理论模型对灵敏度矩阵的状态作了粗略估计。     

偏振态调制的偏振无关干涉型光纤传感器

针对低双折射光纤双束干涉型传感器的两臂偏振态随机变化引起的信号衰落提出了一种新型的光纤传感器结构。通过在双束干涉仪的一臂中加入适当的对光波偏振太的高尖三角波或正弦波调制的偏振制，可以在干涉中见度略有降低的情况下消除偏振衰落的影响，实现偏振无关的干涉型光纤传感器。     

基于光纤温度和应变传感器的物理创新实验

为了实现温度和应变同时测量,本文设计了一种基于多模干涉的光纤温度和应变传感器.该传感器利用光纤熔接机将一段细保偏光纤和一段细芯光纤错位熔接后引入萨格纳克环中而制成.由于光纤错位和模场失配,传感器内存在偏振模干涉和纤芯模-包层模干涉.对不同温度和应变作用下采集到的传感器透射谱进行滤波处理,可提取两种干涉对应的透射谱.基于透射谱中两个不同波谷的温度和应变灵敏度建立同时测量矩阵,即可实现温度和应变的同时测量.实验数据显示该传感器的温度和应变分辨率分别为0.30℃和13.50με.本实验可以作为物理和光电相关专业本科生物理创新实验,帮助大学生掌握光纤传感原理、实验技能和数据处理与分析方法.     

光纤传感物理及其应用

光纤传感器是近十年来迅速发展起来的一种新型传感器．它具有抗电磁干扰、电绝缘性好、灵敏度高、重量轻等一系列优点，因而具有广阔的应用前景．目前已有测量温度、压力、位移、电流、电压等多种物理量的光纤传感器问世．本文介绍了振幅（强度）调制、相位调制、偏振态调制等几类光纤传感器的物理原理、基本特性及其应用概况．     

干涉型光纤传感器的消偏振衰落技术研究

本文对消除干涉型光纤传感器信号偏振衰落的偏振分集接收PDR(Polarization Diversity Receiver)技术进行了理论分析.通过三态PDR方式,对输出的最大有效幅度信号进行选取,能够避免传输光偏振态变化导致干涉信号完全衰落的现象,使干涉信号有效幅度在一定范围内变化.采用基于反正切计算的相位生成载波PGC(Phase Generated Carrier)解调技术的相位测量结果不受由于偏振衰落导致干涉信号有效幅度变化的影响.提出结合三态PDR方式和基于反正切计算的PGC解调技术消除偏振衰落问题的影响,实现干涉型光纤传感器中相位信号的理想解调.     

基于Sagnac原理的单轴分布式光纤传感系统偏振态分析

针对Sagnac干涉型单轴分布式光纤传感器中使用单模光纤作为传感器件时,由于传输光偏振态在双折射影响下所带来的干涉信号“偏振诱导衰落”问题,运用琼斯矩阵分析法,建立了该型传感器系统在传感光纤双折射和外部事件共同作用下,传输光的偏振态对系统功率传输系数影响的数学模型;仿真分析了在传感光纤线性双折射和圆双折射共同作用下,传输光的偏振态对系统功率传输系数的影响;提出了使用法拉第旋转镜提高系统抗偏振能力的改进方法.仿真结果表明,该方法能很好地消除光纤线性双折射和圆双折射.     

基于Sagnac/双Mach-Zehnder原理的分布式光纤传感系统的偏振态分析

运用琼斯矩阵分析法,建立了该分布式传感器系统在传感光纤双折射和外部事件共同作用下,传输光的偏振态对系统功率传输系数影响的数学模型.仿真分析了在传感光纤线性双折射和圆双折射共同作用下,传输光的偏振态对系统功率传输系数的影响,并提出了利用偏振控制器对输入偏振态进行控制,从而改善干涉信号输出的方法.     

干涉型光纤传感器阵列的偏振态反馈叠加控制

提出了在干涉光纤传感器阵列中将各传感器的最佳输入偏振态反馈控制信号叠加用于阵列最佳输入偏振态控制的方案，并对阵列各单元最佳输入偏振态的较差分布时的控制效果进行了理论分析，对达到这一较差分布的概率也进行了计算，分析表明，该方案简单易行，经过信号处理能使各个光纤传感器在降低信噪比的情况下吏可见度均达最大值１，从而消除了阵列中各单元的偏振态衰落。     

偏振模耦合分布式光纤传感器空间分辨率研究

分析了偏振模耦合原理的分布式光纤传感器的自相干与互相干光；实验测量的干涉光证明了理论分析是正确的；利用偏振模耦合原理传感与白光干涉检测的分布式光纤传感器的空间分辨率是由光纤偏振色散系数与光源的谱宽决定的；由实验测量的偏振模耦合分布式光纤传感器的空间分辨率为6cm. 关键词： 光纤传感器 保偏光纤 空间分辨率 偏振模耦合     

一种基于马赫-曾德干涉仪的全光纤传感器双参数测量技术

提出一种干涉式全光纤传感器,能够同时实现对折射率和轴向拉力或温度进行双参数测量。传感器由一个微腔和一个纤芯失配衰减器组成。其中微腔结构是由飞秒激光加工光纤纤芯形成,直径和深度分别是6μm和2.5μm。该干涉式传感器可以获得20dB的高品质干涉对比度。传感器透射谱波长为1496.68nm和1533.18nm的两个衰减峰对应的折射率灵敏度分别为-29.91nm/RIU和-16.72nm/RIU,拉力灵敏度分别为-1.55pm/με和-0.31pm/με。实验结果表明,传感器通过灵敏度矩阵可以同时测量折射率和轴向拉力或温度两个参数。     

Demonstration of high extinction ratio modal interference in a two-mode fiber and its applications for all-fiber comb filter and high-temperature sensor

We show that high extinction ratio (>20 dB) modal interference in a two-mode dispersion compensating fiber can be utilized to build a compact, easy-to-fabricate tunable all-fiber optical comb filter. Wavelength tunability over the full free spectral range of the comb filter is demonstrated with an electrical power of 115mW using an on-fiber thin film micro-heater deposited directly on the fiber. In another configuration, the comb filter is used as a temperature sensor with dynamic range of >300 °C and sensitivity of <0.1 °C. The temperature sensor is capable of measuring a temperature as high as 500 °C.     

双波长偏振干涉型应变与温度同时测量的光纤传感器

针对保偏光纤给出了利用双波长偏振干涉型传感器同时测量应变和温度的一般理论，并通过实验证明了这一理论的可行性。对３０ｃｍ长的ｂｏｗ－ｔｉｅ型光纤的实验结果表明，在温度变化７０℃，光纤长度变化５００μｍ测量范围内，最大误差分别为±２．５℃和±８μｍ。由于这一传感器只利用了正交基模的偏振干涉，因此具有较好的稳定性。     

Ultrahigh sensitivity polarimetric strain sensor based upon D-shaped optical fiber and surface plasmon resonance technology

An ultrahigh sensitivity polarimetric strain sensor is proposed based upon a four-layer D-shaped optical fiber and surface plasmon resonance (SPR) technology. In contrast to existing SPR-based sensors, which are based on changes in the refractive index of the overlayer, the sensor proposed in this study is based on the change in the refractive index of the fiber core in response to the application of an axial load. Specifically, the phase difference between the P and S waves after passing through the sensor under SPR conditions is measured using a common-path heterodyne interferometer and is used to determine the corresponding change in the refractive index of the core, from which the strain is then inversely derived. The experimental results show that the sensitivity of the proposed sensor is around 2.19×10? deg/ε, i.e., degree/strain. By contrast, that of a conventional (non-SPR) polarimetric fiber sensor is just 5.2×102 deg/ε. To the best of the authors' knowledge, the sensor proposed in this study represents the first reported attempt to exploit the refractive index change of the core of an SPR-based fiber sensor for strain measurement purposes.     

Highly Sensitive and Widely Dynamic Fiber-Coiled Deformation Sensor Immune from External Disturbances

This paper describes a double fiber-coiled interferometric deformation sensor fabricated using paired polarization maintaining single-mode fibers. A change in bending-induced birefringence plays a fundamental role in the sensor performance as the fiber-coil is being deformed across its cross-section. Differential optical heterodyne detection processes allow us to implement two-mode operations; one is widely dynamic operation and the other highly sensitive operation around a target region. The deformation sensitivity for one-turn fiber-coil is 2.5 deg/mm for the widely dynamic operation, whereas 9.5X10 deg/mm for the highly sensitive operation. The double fiber-coiled deformation sensor can eliminate external, undesirable temperature disturbances.     

Optical-fiber strain sensor using combined interference and polarimetric technique

An optical-fiber strain sensor, using a combined interference and polarimetric technique, is presented. The main advantage of this sensor is that it possesses the sensitivity of an interferometer and at the same time the sign of the strain can be determined without any electronic logic circuits. The strain values sensed by this technique match very well with an electrical strain gage signal.     

Ultrasensitive refractive-index sensors based on rectangular silica microfibers

We demonstrate an ultrasensitive refractive-index (RI) sensor utilizing the polarimetric interference of a rectangular silica microfiber. The measured sensitivity is as high as 18,987 nm/RIU (refractive-index unit) around the RI of 1.33, which is 1 order of magnitude higher than that of the previously reported microfiber devices. Theoretical analysis reveals that such high sensitivity not only is originated from the RI-induced birefringence variation but also relies on the unique birefringence dispersion property for the rectangular microfiber. We predict that the sensitivity can be enhanced significantly when the group birefringence approaches zero.     

Optical path automatic compensation low-coherence interferometric fibre-optic temperature sensor

An interferometric fibre-optic temperature sensing system employing a light emitting diode (LED) as the broadband optical source and a single mode fibre coil which was fabricated in a definite length as the sensor head is described. A reference fibre line transmitting back and forth along the same path as the sensing transmitting fibre is used, so the change caused by the environmental temperature fluctuation of the fibre path can automatically be compensated. The sensitivity of the sensing system can be easily improved by using the long length of the sensing fibre. The experiment results of the sensing gauge length versus the sensitivity are given. Two typical wavelengths (1300 and 1550 nm). LED sources are used, it is shown that the sensitivity of the system between the two wavelengths is different. The experimental curve of the resolution characteristic of the system related to the length of sensing fibre coil is also discussed.     

High sensitivity plasmonic temperature sensor based on a side-polished photonic crystal fiber

A high sensitivity plasmonic temperature sensor based on a side-polished photonic crystal fiber is proposed in this work.In order to achieve high sensitivity and high stability,the gold layer is coated on the side-polished photonic crystal fiber to support surface plasmon resonance.The mixture of ethanol and chloroform is used as the thermosensitive liquid.The performances of the proposed temperature sensor were investigated by the finite element method(FEM).Simulation results indicate that the sensitivity of the temperature sensor is as high as 7.82 nm/℃.It has good linearity(R;=0.99803),the resolution of 1.1×10;℃,and the amplitude sensitivity of 0.1008℃;.In addition,the sizes of the small air hole and polishing depth have little influence on the sensitivity.Therefore,the proposed sensor shows a high structure tolerance.The excellent performance and high structure tolerance of the sensor make it an appropriate choice for temperature measurement.     

On the fiber-optic chlorine sensor with enhanced sensitivity based on the study of evanescent field absorption spectroscopy

The paper deals with a fiber optic evanescent field absorption sensor that can be used for the detection of chlorine content in drinking water. The technique is based on the absorption of evanescent fields through the development of color owing to the reaction of an organic compound diethyl phenylene diamine with chlorine, which is already present in water. In the experiment, a U-shaped optical sensor probe is used because the sensitivity of the system improves due to the higher penetration depth achieved in this case. The improvement in sensitivity (in the case of U-shaped probed) is also shown experimentally.