A Nonlinear Mirror Structure to Improve the Performance of the Distributed Fiber Temperature Sensor Based on Raman Backscattering

A novel nonlinear mirror structure which can increase the optical signal-to-noise ratio of a distributed fiber Raman temperature sensor is proposed, and 6 dB improvement of the optical signal-to-noise ratio is obtained. With the assistance of the nonlinear mirror, we demonstrate that the spatial resolution of the sensor is improved from 3 m to 1 m, and the temperature accuracy is improved from ±0.6℃ to ±0.2℃. The theoretical analysis and the experimental data are in good agreement.

Network Integration of Distributed Optical Fiber Temperature Sensor

The integration of distributed optical fiber temperature sensor with supervisory control and data acquisition （SCADA） system is proposed and implemented. In the implementation of the integration, both the compatibility with traditional system and the characteristics of distributed optical fiber temperature sensor is considered before Modbus TCP/IP protocol is chosen. The protocol is implemented with open source component Indy. The Modbus TCP/IP protocol used in the system is proved to be fast and robust.

Fibre optic distributed scattering sensing system:perspectives and challenges for high performance applications

As fiber optic distributed scattering sensing systems are providing innovative solutions for the monitoring of large structures,the comparison of different techniques and solutions is difficult because of the lack of standardized specifications and the difficulty associated to the characterization of such systems.The article presents a tentative definition of performance specifications and qualification procedures applicable to fiber optic distributed sensing systems aiming at providing clear guidelines for their design,specifications,qualification,application and selection.

Recent Progress in Distributed Optical Fiber Raman Photon Sensors at China Jiliang University

在在中国 Jiliang 大学(CJLU ) 的完整的分布式的纤维拉曼光子传感器的研究，生产和应用的最近的进步的简短评论被介绍。以便改进测量距离，精确性，空间分辨率，多参数大小的能力，和完整的分布式的纤维传感器系统的智力，一种新一代纤维传感器技术基于光纤维，非线性的散布熔化原则被建议。一系列新一代完整的分布式的纤维传感器被调查并且设计，它由新产生组成极端长的距离散布与一个纤维拉曼放大器综合的光子传感器的完整的分布式的纤维拉曼和瑞利，汽车修正完整的分布式的纤维拉曼光子温度传感器基于拉曼关联双来源，完整的分布式的纤维拉曼光子温度传感器基于编码的脉搏采购原料，完整的分布式的纤维拉曼光子温度传感器

Going beyond 1000000 resolved points in a Brillouin distributed fiber sensor: theoretical analysis and experimental demonstration

Distributed fiber sensing possesses the unique ability to measure the distributed profile of an environmental quantity along many tens of kilometers with spatial resolutions in the meter or even centimeter scale.This feature enables distributed sensors to provide a large number of resolved points using a single optical fiber.However,in current systems,this number has remained constrained to a few hundreds of thousands due to the finite signal-to-noise ratio(SNR)of the measurements,which imposes significant challenges in the development of more performing sensors.Here,we propose and experimentally demonstrate an ultimately optimized distributed fiber sensor capable of resolving 2100000 independent points,which corresponds to a one-orderof-magnitude improvement compared to the state-of-the-art.Using a Brillouin distributed fiber sensor based on phase-modulation correlation-domain analysis combined with temporal gating of the pump and time-domain acquisition,a spatial resolution of 8.3 mm is demonstrated over a distance of 17.5 km.The sensor design addresses the most relevant factors impacting the SNR and the performance of medium-to-long range sensors as well as of sub-meter spatial resolution schemes.This step record in the number of resolved points could be reached due to two theoretical models proposed and experimentally validated in this study:one model describes the spatial resolution of the system and its relation with the sampling interval,and the other describes the amplitude response of the sensor,providing an accurate estimation of the SNR of the measurements.

Performance Improvement of Raman Distributed Temperature System by Using Noise Suppression

在拉曼散布了温度系统，为表演改进的关键因素是噪音抑制，它严重影响察觉到的距离和温度精确性。因此，我们建议并且试验性地示威动态噪音差别算法和小浪变换模量最大值(WTMM ) 到降噪拉曼反 -- 司烧信号。察觉到的距离能从 3 km 增加到 11.5 km 和温度精确性的试验性的结果表演增加到 1.58 ? 臨? 臨?

Random Raman Fiber Laser as a Liquid Refractive Index Sensor

In this paper,a new concept of forward-pumped random Raman fiber laser(RRFL)-based liquid refractive index sensing is proposed for the first time.For liquid refractive index sensing,the flat fiber end immersed in the liquid can act as the point reflector for generating random fiber lasing and also as the sensing head.Due to the high sensitivity of the output power of the RRFL to the reflectivity provided by the point reflector in the ultralow reflectivity regime,the proposed RRFL is capable of achieving liquid refractive index sensing by measuring the random lasing output power.We theoretically investigate the effects of the operating pump power and fiber length on the refractive index sensitivity for the proposed RRFL.As a proof-of-concept demonstration,we experimentally realize high-sensitivity half-open short-cavity RRFL-based liquid refractive index sensing with the maximum sensitivity and the sensing resolution of-39.88W/RIU and 2.5075×10^(-5) RIU,respectively.We also experimentally verify that the refractive index sensitivity can be enhanced with the shorter fiber length of the RRFL.This work extends the application of the random fiber laser as a new platform for highly-sensitive refractive index sensing in chemical,biomedical,and environmental monitoring applications,etc.

基于系统工程方法论的分布式光纤后向Raman散射测温系统设计(英文)

基于后向 Raman散射测温系统的最大弱点是后向散射信号非常微弱 ,直接影响系统的应用 .本文引入系统工程的观点和方法 ,遵循系统建模、系统分析、系统优化和系统设计的思路 ,实现了整个系统的优化设计 .首先 ,将系统划分成光源和 Raman滤光片两个子系统 .其次 ,分别针对它们建立数学模型 ,进行分析和优化 .最后 ,综合考虑实际子系统间的关系 ,得到整个系统的最优设计 .方法具有一定的先进性 ,实践证明 ,以此为基础设计的系统可以得到极佳的测量效果 .

基于后向Raman散射测温系统波长的优化分析

本文对基于后向 Raman散射分布式光纤测温系统中激光器中心波长的优化进行了分析 .在详细讨论了 Raman信号强度、温度灵敏度和系统工作稳定性等与半导体激光器中心波长之间的关系后 ,提出了优化选择中心波长的方法 ,并结合实例予以说明 .

Development of Fully-Distributed Fiber Sensors Based on Brillouin Scattering

Brillouin scattering based optical fiber sensors(BOFS)have the unique advantages over other sensors such as long distance,fully distributed,and multi-parameter sensing.The progresses on the development of BOFS technology in Nanjing University are reviewed.The key technologies to make BOFS with ultra-long distance,high spatial resolution,and fast measuring speed are discussed and realized.

基于自发Raman散射分布式光纤测温系统设计

光纤传感器是一种新发展起来的传感技术。文章介绍了基于自发Raman散射的分布式光纤测温系统的应用及其结构设计,并着重分析了在脉冲光作用下系统的测温原理,同时设计了一个新型的基于薄膜滤光片的用于Raman散射的波分复用(WDM)组件。

基于后向Raman散射的分布式测温系统滤光片的数学模型

本文给出了一个设计Ｒａｍａｎ滤光片参数（中心波长和全峰值半宽ＦＷＨＭ）的数学模型．首先，讨论了Ｒａｍａｎ滤光片参数设计的相关问题，接着提出了数学模型并进行了讨论．分析表明：模型是合理、有效的．最后，给出了一个具体实例．

Raman散射线型光纤感温火灾探测器的优化设计

分析了分布式光纤温度传感技术在火灾探测报警领域的应用特性和系统优化设计方案,介绍了光时域反射技术以及光纤中的Raman散射测温原理。设计开发了AT810线型光纤感温火灾探测器基于专用算法处理芯片ASIC和PowerPC处理器的实时数据采集处理系统,采用嵌入式硬件系统和基于嵌入式linux的软件平台优化系统硬件和软件性能,并对感温光缆进行优化设计,提高了系统的稳定性及可靠性。

分布光纤Raman光子温度传感器(DOFRPTS)系统的信号和噪声分析

在DOFRPTS系统中，自发反斯托克斯Raman散射光子是温度信息的载体．Rayligh散射光子是压力、应力信息的载体，在2公里长光纤上，实时采样1000个点．可同时测量空间温度场的分布和空间力场的分布．系统中分别采用Rayleigh散射OTDR技术和Raman散射OTDR技术．对所测点进行定位．本文对DOFRPTS系统中的信号、噪声进行了分析，测温精度由系统的信噪比来确定，本系统的测温精度达±1℃．

Ultrahigh-speed distributed Brillouin reflectometry

Optical fibre sensors based on Brillouin scattering have been vigorously studied in the context of structural health monitoring on account of their capacity for distributed strain and temperature measurements.However,real-time distributed strain measurement has been achieved only for two-end-access systems;such systems reduce the degree of freedom in embedding the sensors into structures,and furthermore render the measurement no longer feasible when extremely high loss or breakage occurs at a point along the sensing fibre.Here,we demonstrate real-time distributed measurement with an intrinsically one-end-access reflectometry configuration by using a correlation-domain technique.In this method,the Brillouin gain spectrum is obtained at high speed using a voltage-controlled oscillator,and the Brillouin frequency shift is converted into a phase delay of a synchronous sinusoidal waveform;the phase delay is subsequently converted into a voltage,which can be directly measured.When a single-point measurement is performed at an arbitrary position,a strain sampling rate of up to 100 kHz is experimentally verified by detecting locally applied dynamic strain at 1 kHz.When distributed measurements are performed at 100 points with 10 times averaging,a repetition rate of 100 Hz is verified by tracking a mechanical wave propagating along the fibre.Some drawbacks of this ultrahigh-speed configuration,including the reduced measurement accuracy,lowered spatial resolution and limited strain dynamic range,are also discussed.

基于拉曼散射的分布式光纤传感系统真空低温热沉环境温度梯度测量

新型分布式光纤温度传感器具备电类温度传感器所不具有的独特优势,扩展了温度测量在真空低温环境中的应用领域。在真空低温热沉环境下使用分布式光纤温度传感器进行温度梯度测量。传统热电偶温度传感器和分布式光纤温度传感器布置在同一双层铝板结构中,铝板以及传感器放置在真空低温热沉环境中。铝板由加热片进行控温,以实现真空低温热沉环境下不同温度梯度的测量。对两类传感器所测铝板的温度数据进行分析,结果表明,基于拉曼散射原理的分布式光纤温度测量系统能够对真空低温热沉环境下的温度梯度实现精确测量,可以满足低温工况下工件的温度测量。

光纤复合型110 kV油纸套管研制及内部温度分布特性

油纸电容式套管是油浸式变压器的重要部件,为实现套管内部温度监测,提出将单模光纤和多模光纤并行缠绕于电容芯子外侧,利用布里渊光时域分析和拉曼光时域反射光纤传感技术对其进行全时空温度监测的设计方案。利用有限元仿真计算得到布设光纤前后套管局部场强变化幅度较小,由0.673 kV/mm改变为0.752 kV/mm;同时对光纤进行了热老化试验,验证了方案的可行性,并研制出1根光纤复合型110 kV油纸套管。在施加电压为126 kV时,套管局部放电量为5.03 pC,局部放电试验结果满足国标要求。通过温升试验测量得到套管温度数据并进行了温度场仿真研究,实测数据表明套管表面轴向温差达到45.2℃,而内侧芯子轴向温差仅为6.7℃,结合仿真结果推理得到套管内部存在上、下油循环且油流方向相反。该套管的研制可为油纸电容式套管的状态监测提供新的思路与参考。

A high sensitive fiber Bragg grating strain sensor with automatic temperature compensation

A high sensitive fiber Bragg grating （FBG） strain sensor with automatic temperature compensation is demonstrated. FBG is axially linked with a stick and their free ends are fixed to the measured object. When the measured strain changes, the stick does not change in length, but the FBG does. When the temperature changes, the stick changes in length to pull the FBG to realize temperature compensation. In experiments, 1.45 times strain sensitivity of bare FBG with temperature compensation of less than 0.1 nm Bragg wavelength drift over 100 ℃ shift is achieved.

准分布式光纤光栅传感技术在水电厂测温系统中的应用

为了提高测温系统的测量精度与抗干扰性,提出将准分布式光纤光栅传感技术应用在水电厂测温系统中。根据光纤传感器特点,设计系统光路和数据采集模块,引入FPGA芯片和PCIE接口建立编程文件存储模块;应用准分布式光纤光栅传感技术,计算光路最佳分光比,去除光路内信号的噪声,计算目标温度值。实验结果表明:在空间距离越来越大的情况下,测量精度仍然较高,为±0.1℃,温度信号未发生失真情况,测温系统的抗干扰性能得到了提高。