Temperature and Salinity Dual-parameter Sensing Based on Forward Brillouin Scattering in 1060-XP SMF

A novel temperature and salinity discriminative sensing method based on forward Brillouin scattering(FBS)in 1060-XP single-mode fiber(SMF)is proposed.The measured frequency shifts corresponding to different radial acoustic modes in 1060-XP SMF show different sensitivities to temperature and salinity.Based on the new phenomenon that different radial acoustic modes have different frequency shift-temperature and frequency shift-salinity coefficients,we propose a novel method for simultaneously measuring temperature and salinity by measuring the frequency shift changes of two FBS scattering peaks.In a proof-of-concept experiment,the temperature and salinity measurement errors are 0.12℃and 0.29%,respectively.The proposed method for simultaneously measuring temperature and salinity has the potential applications such as ocean surveying,food manufacturing and pharmaceutical engineering.

OBS浊度计在三水、马口及岗根水文站含沙量比测试验研究

根据光学后向散射浊度计测量水体浊度与人工传统含沙量分析在三水、马口及岗根水文站同步比测试验研究分析,揭示了珠江三角洲部分河道水体浊度与含沙量的相互关系,探讨了光学后向散射浊度计应用于珠江三角洲河道含沙量分析的前景。

OBS 500光学后向散射浊度仪在马口水文站泥沙监测应用分析

采用相关关系分析方法,通过马口水文站传统含沙量分析与OBS 500光学后向散射浊度仪泥沙监测应用比测分析,建立水体浊度与泥沙浓度的相关关系,进行浊度与泥沙浓度的转化,进而实现含沙量在线监测方式。OBS泥沙监测方法简单、处理速度快、可实现实时连续监测,对于在复杂珠江三角洲网河区域实现泥沙在线监测具有现实的推广意义。

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.

Signal Processing for Fibre-optic Distributed Sensing Techniques Employing Brillouin Scattering

As fibre optic distributed scattering sensing systems are providing innovative solutions for the monitoring of large structures,Brillouin-based distributed scattering sensing techniques represent a new physical approach for structures health monitoring,which seems extremely promising and is receiving most attentions.This paper comprehensively presents some methods of signal interrogation for fibre optic Brillouin-based distributed scattering sensing technology,especially establishes an accurate Pseudo-Voigt model of Brillouin gain spectrum and gives some results on spectrum analysis and data processing.

融合拉曼散射的BOTDR温度应变解耦传感系统研究

采用单模光纤获取布里渊频移并利用多模光纤进行拉曼测温补偿,是工程应用中常用的温度应变双参量传感方法。但其存在传感光缆结构复杂、应用成本高的缺点。基于双路光开关分时复用,搭建了面向单芯单模光纤的拉曼散射和布里渊频移融合探测系统,实现了温度与应变解耦测量。分析了双参量传感测量原理,构建了拉曼散射辅助的BOTDR实验系统,并采用小波降噪算法进行数据处理。实验证明,该系统在3 m空间分辨率下,测量距离可达9 km,温度测量结果波动范围为±1.5℃,温度波动均方根误差(RMSE)为0.808℃,应变解调结果波动范围为±117με,应变波动均方根误差(RMSE)为72.04με。研究表明,融合拉曼散射的BOTDR温度应变解耦传感系统可有效解决单模光纤传感过程中交叉敏感问题,为后续的工程化应用提供了理论基础和解决方案。

单光路拉曼分布式光纤测温系统

针对常规拉曼分布式光纤测温系统中,拉曼Stokes和anti-Stokes散射光的走离效应导致位置校正困难,测温严重失真的问题,提出了基于单光路的拉曼分布式测温系统方案,建立散射光功率校正模型和温度标定算法,实现对被测光纤沿线温度的精确测量。根据拉曼散射光温度敏感原理,推导基于单路Stokes光及单路anti-Stokes光的温度解调公式。考虑到单光路温度解调严重受限于脉冲激光器和光电探测器稳定性的问题,设计温度标定单元并建立了信号光功率校正算法。搭建实验平台,对比分析传统双路、单路Stokes光及单路anti-Stokes光方案的测温性能。最后,讨论并总结基于单光路拉曼分布式光纤测温系统的优选方案。实验结果表明:在约12 km的光纤线路上,基于拉曼anti-Stokes光的方案的测温偏差为-0.3~2.2℃,均方根误差为1.0℃,空间分辨率为6 m,与传统方案相比性能更优。基于信号功率校正的单光路拉曼anti-Stokes光的分布式光纤测温系统灵敏度高,能完全规避传统双光路系统的走离校正问题,具备很高的实用价值。

High‐sensitivity distributed dynamic strain sensing by combining Rayleigh and Brillouin scattering

The phase-sensitive optical time-domain reflectometry(φ-OTDR)is a good candidate for distributed dynamic strain sensing,due to its high sensitivity and fast measurement,which has already been widely used in intrusion monitoring,geophysical exploration,etc.For the frequency scanning basedφ-OTDR,the phase change manifests itself as a shift of the intensity distribution.The correlation between the reference and measured spectra is employed for relative strain demodulation,which has imposed the continuous measurement for the absolute strain demodulation.Fortunately,the Brillouin optical time domain analysis(BOTDA)allows for the absolute strain demodulation with only one measurement.In this work,the combination of theφ-OTDR and BOTDA has been proposed and demonstrated by using the same set of frequency-scanning optical pulses,and the frequency-agile technique is also introduced for fast measurements.A 9.9 Hz vibration with a strain range of 500 nεhas been measured under two different absolute strains(296.7μεand 554.8με)by integrating the Rayleigh and Brillouin information.The sub-micro strain vibration is demonstrated by theφ-OTDR signal with a high sensitivity of 6.8 nε,while the absolute strain is measured by the BOTDA signal with an accuracy of 5.4με.The proposed sensor allows for dynamic absolute strain measurements with a high sensitivity,thus opening a door for new possibilities which are yet to be explored.

Active wavefront shaping for controlling and improving multimode fi ber sensor

Wavefront shaping(WFS)techniques have been used as a powerful tool to control light propagation in complex media,including multimode fibers.In this paper,we propose a new application of WFS for multimode fber-based sensors.The use of a single multimode fiber alone,without any special fabrication,as a sensor based on the light intensity variations is not an easy task.The twist effect on multimode fiber is used as an example herein.Experimental results show that light intensity through the multimode fiber shows no direct relationship with the twist angle,but the correlation coefficient(CC)of speckle patterns does.Moreover,if WFS is applied to transform the spatially seemingly random light pattern at the exit of the multimode fiber into an optical focus.The focal pattern correlation and intensity both can serve to gauge the twist angle,with doubled measurement range and allowance of using a fast point detector to provide the feedback.With further development,WFS may find potentials to facilitate the development of multimode fber-based sensors in a variety of scenarios.

Simple Raman scattering sensor integrated with a metallic planar optical waveguide: effective modulation via minor structural adjustment

We report experimental realization of Raman spectra enhancement of copper phthalocyanine, using an on-chip metallic planar waveguide of the sub-millimeter scale. The oscillating ultrahigh order modes excited by the direct coupling method yield high optical intensity at resonance, which is different from the conventional strategy to create localized ＂hot spots.＂ The observed excitation efficiency of the Raman signal is significantly enhanced,owing to the high Q factor of the resonant cavity. Furthermore, effective modulation of the Raman intensity is available by adjusting the polymethyl methacrylate（PMMA） thickness in the guiding layer, i.e., by tuning the light–matter interaction length. A large modulation depth is verified through the fact that 10 times variation in the enhancement factor is observed in the experiment as the PMMA thickness varies from 7 to 23 μm.

光纤SERS传感器结构及典型应用

光纤具有体积小、灵活性高、无电磁干扰、重量轻、适用于信号远程传输等优势,可以与SERS(Surface-enhanced Raman scattering)技术相结合,制备成光纤SERS传感器,广泛应用于无标签的化学、生物传感领域。光纤SERS传感器具有传统SERS技术的优点,且兼具多路复用能力和特殊环境下的连续动态监测能力。本文主要综述了光纤SERS传感器结构及其典型应用。首先,探究了光纤SERS传感器的发展及其必要性;其次,介绍了目前常见的光纤SERS传感器及其制备方法;最后,简要介绍了光纤SERS传感器在典型领域的应用及未来展望。

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

A brief review of recent progress in researches, productions and applications of full distributed fiber Raman photon sensors at China Jiliang University （CJLU） is presented. In order to improve the measurement distance, the accuracy, the space resolution, the ability of multi-parameter measurements, and the intelligence of full distributed fiber sensor systems, a new generation fiber sensor technology based on the optical fiber nonlinear scattering fusion principle is proposed. A series of new generation full distributed fiber sensors are investigated and designed, which consist of new generation ultra-long distance full distributed fiber Raman and Rayleigh scattering photon sensors integrated with a fiber Raman amplifier, auto-correction full distributed fiber Raman photon temperature sensors based on Raman correlation dual sources, full distributed fiber Raman photon temperature sensors based on a pulse coding source, full distributed fiber Raman photon temperature sensors using a fiber Raman wavelength shifter, a new type of Brillouin optical time domain analyzers （BOTDAs） integrated with a fiber Raman amplifier for replacing a fiber Brillouin amplifier, full distributed fiber Raman and Brillouin photon sensors integrated with a fiber Raman amplifier, and full distributed fiber Brillouin photon sensors integrated with a fiber Brillouin frequency shifter. The Internet of things is believed as one of candidates of the next technological revolution, which has driven hundreds of millions of class markets. Sensor networks are important components of the Internet of things. The full distributed optical fiber sensor network （Rayleigh, Raman, and Brillouin scattering） is a 3S （smart materials, smart structure, and smart skill） system, which is easy to construct smart fiber sensor networks. The distributed optical fiber sensor can be embedded in the power grids, railways, bridges, tunnels, roads, constructions, water supply systems, dams, oil and gas pipelines and other facilities, and can be integrated with wireless networks.

地下水原位监测浊度传感器设计

针对传统浊度传感器应用于地下水原位监测时存在尺寸大、预热时间长等问题,设计了一种适用于地下水原位监测的新型浊度传感器。传感器基于90°散射光测量原理,采用柔性玻璃光纤束作为导光材料,显著减小了传感器的尺寸。此外,传感器对光源发光强度进行了动态监测补偿,从而有效缩短了传感器预热时间,同时进一步提高了传感器的测量精度。介绍了传感器的测量原理和设计方法,并结合地下水原位监测使用需求及相关规范要求对传感器性能进行了验证。传感器测量重复性为0.41%、漂移为0.46%、线性误差为0.47%,可较好地耐受0.5 MPa水压环境。试验结果表明:传感器测量精度高、稳定性好、耐水压能力强,适用于地下水原位浊度监测。

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.

隧道健康诊断BOTDR分布式光纤应变监测技术研究

布里渊散射光时域反射监测技术是一项新型的光电监测技术,它利用布里渊散射光的光谱技术和光时域测量技术,可对沿光纤的轴向应变进行分布式监测,并具有分布式、长距离、精度高和耐久性长等特点。首先介绍了该监测技术的原理和特点,并以南京市鼓楼隧道健康诊断为例,介绍了该技术应用于该隧道变形监测以及监测的方案,讨论了隧道内环境因素如温差和振动等对监测结果的影响,验证了监测系统的灵敏性,最后对隧道的变形监测结果进行了分析,给出了鼓楼隧道的健康诊断。研究成果表明:该技术应用在隧道安全监测和健康诊断中是十分可行的,也是十分有效的。

基于拉曼散射原理的分布式光纤测温系统研究

在研究拉曼散射原理及其应用技术的基础上,开发了一种分布式结构的光纤测温系统。通过对光纤的拉曼散射光谱信息进行解调处理,实现了全光纤的分布式温度检测。系统达到的温度分辨率为0.3℃,空间分辨率为3m,最大测量距离为6 000m。相关的实验室和野外试验结果表明,该系统的主要性能指标能够满足实际工程的使用要求。

基于布里渊散射的分布式光纤传感器的进展

目的 介绍了基于布里渊散射的分布式光纤传感器的当前进展及趋势 .方法 给出了基于布里渊散射的分布式光纤传感器的原理 ,介绍了基于光纤光时域反射的 BOTDR和 BOTDA的分布式光纤传感器 ,以及基于自发布里渊散射的同时测试应变和温度分布式光纤传感器 ,并指出了遇到的问题 .结果 使读者详细了解基于布里渊散射的分布式光纤传感器当前进展及发展趋势 .结论 基于布里渊散射的分布式光纤传感器继承了分布式光纤传感器的优点 ,并使测试的范围增大 ,可测信息种类增多 ,精度更高 .

布里渊散射分布式光纤传感技术的研究进展

阐述了基于布里渊散射的分布式光纤传感技术测量光纤温度/应变的基本传感原理。介绍了基于光时域反射仪发展起来的几种传感技术,布里渊光时域反射(BOTDR)、布里渊光时域分析(BOTDA)、布里渊光频域分析(BOFDA)分布式光纤传感技术,特别对BOTDR的原理和典型系统方案进行了详细的介绍。最后,叙述了基于布里渊散射的分布式光纤传感技术当前的进展和趋势。

分布式光纤喇曼温度传感器的循环解调法

为了抑制温漂噪声积累,瑞利背向散射光窜扰反斯托克斯背向散射光,考虑了最近测量瑞利背散射光曲线解调反斯托克斯背向散射光温度曲线方法,即循环解调方法;该方法提高了系统的测温精度、稳定性,降低了系统的成本.实验结果与理论分析一致,系统的测温精度达±0.05℃.

光纤生物量浓度在线检测传感器

建立了一种新的生物量浓度测量方法,并对传感器的设计进行了研究,介绍了传感器的组成原理、光路、理论分析和相关实验。基于光的吸收和散射与介质的浓度、通过介质的光程和入射光强有关,生物量浓度的变化会引起吸收和散射的变化,从而导致接收光能量的变化这一物理现象和理论,将接收光能量的大小与具有实用意义的生物量浓度测量联系起来,建立了一种新的生物量浓度测量方法。实验选用了760 nm近红外光源,在20℃恒温情况下,对生物量浓度测量进行了实验研究。结果表明,这种方法用于测量微生物菌液浓度具有很好的对应函数关系,测量的最大相对误差<0.2%,具有生物量浓度在线测量准确、灵敏高、使用寿命长等优点。传感器的设计原理和方法具有一定的普遍意义,是一种有实用价值的生物量浓度传感器,可实现对含有微生物的菌液进行生物量浓度在线测量。