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Fiber Optic Hydrogen Sensors： a Review

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Photonic Sensors 2014年第4期4卷 300-324页

作者： Minghong YANG Jixiang DAI National Engineering Laboratory for Optical Fiber Sensing Technologies Wuhan University of Technology Wuhan430070 China

Hydrogen is one of the next generation energies in the future, which shows promising applications in aerospace and chemical industries. Hydrogen leakage monitoring is very dangerous and important because of its low ignition energy, high combustion efficiency, and smallest molecule. This paper reviews the state-of-art development of the fiber optic hydrogen sensing technology. The main developing trends of fiber optic hydrogen sensors are based on two kinds of hydrogen sensitive materials, i.e. palladium-alloy thin films and Pt-doped WO3 coatings. In this review work, the advantages and disadvantages of these two kinds of sensing technologies will be evaluated.

关键词： Optical fiber sensors hydrogen sensing thin films coatings

Experimental Study on Dual-Wavelength Distributed Feedback Fiber Laser

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Photonic Sensors 2014年第3期4卷 225-229页

作者： Haifeng QI Zhiqiang SONG Jian GUO Chang WANG Jun CHANG Gangding PENG Shandong Key Laboratory of Optical Fiber Sensing Technologies Laser Institute of Shandong Academy of SciencesJinan 250014 China

Four distributed feedback fiber lasers with dual-wavelength operations were studied experimentally in detail. The laser characteristics of these distributed feedback fiber lasers （DFB-FLs） were investigated. The operation conditions for the dual-wavelength output are analyzed and presented. Through this study, the guidance of the design and fabrication of some dual-wavelength distributed feedback fiber lasers are provided.

关键词： Distributed feedback fiber laser dual wavelength phase shift optical fiber sensing

Micro-Displace Sensor Based on Self-Mixing Interference of the Fiber Laser With Phase Modulation

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Photonic Sensors 2014年第4期4卷 379-384页

作者： Hui HAO Dongmei GUO Ming WANG Wei XIA Xiaoqi NI Jiangsu Key Lab of Opto-Electronic Technology School of Physical Science and Technology Nanjing NormalUniversity Nanjing 210023 China

Micro-displacement measurement based on self-mixing interference using a fiber laser system was demonstrated. The sinusoidal phase modulation technique was introduced into the fiber laser self-mixing interference measurement system to improve the measurement resolution. The phase could be demodulated by the Fourier analysis method. Error sources were evaluated in detail, and the system was experimentally applied to reconstruct the motion of a high-precision commercial piezoelectric ceramic transducer （PZT）. The displacement measurement resolution was well beyond a half-wavelength. It provides a practical solution for displacement measurement based on all optical-fiber sensing applications with high precision.

关键词： Self-mixing interference micro-displacement sensing phase modulation fiber laser

Design, Fabrication, and Measurement of Two Silicon-Based Ultraviolet and Blue-Extended Photodiodes

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Photonic Sensors 2014年第4期4卷 373-378页

作者： Changping CHEN Han WANG Zhenyu JIANG Xiangliang JIN Jun LUO Faculty of Materials Optoelectronics and Physics Xiangtan University Xiangtan 411105 China Hunan Engineering Laboratory for Microeleetronics Optoelectronics and System on A Chip Xiangtan 411105 China The forty-eighth Research Institute of China Electronics Technology Group Corporation Changsha 410111 China Department of Precision Mechanical Engineering Shanghai University ShanghaL 200444 China

Two silicon-based ultraviolet （UV） and blue-extended photodiodes are presented, which were fabricated for light detection in the ultraviolet/blue spectral range. Stripe-shaped and octagon-ring-shaped structures were designed to verify parameters of the UV-responsivity, UV-selectivity, breakdown voltage, and response time. The ultra-shallow lateral pn junction had been successfully realized in a standard 0.5-μm complementary metal oxide semiconductor （CMOS） process to enlarge the pn junction area, enhance the absorption of UV light, and improve the responsivity and quantum efficiency. The test results illustrated that the stripe-shaped structure has the lower breakdown voltage, higher UV-responsicity, and higher UV-selectivity. But the octagon-ring-shaped structure has the lower dark current. The response time of both structures was almost the same.

关键词： Ultraviolet/blue photodiode ultraviolet responsivity breakdown voltage transient response CMOS

Broken Wires Diagnosis Method Numerical Simulation Based on Smart Cable Structure

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Photonic Sensors 2014年第4期4卷 366-372页

作者： Sheng LI Min ZHOU Yan YANG National Engineering Laboratory for Fiber Optic Sensing Technology Wuhan University of Technology Wuhan430070 China Wuhan WUTO.S Limited Company Wuhan 430223 China Key Laboratory of Fiber Optic Sensing Technology and Information Processing Ministry of Education WuhanUniversity of Technology Wuhan 430070 China

The smart cable with embedded distributed fiber optical Bragg grating （FBG） sensors was chosen as the object to study a new diagnosis method about broken wires of the bridge cable. The diagnosis strategy based on cable force and stress distribution state of steel wires was put forward. By establishing the bridge-cable and cable-steel wires model, the broken wires sample database was simulated numerically. A method of the characterization cable state pattern which can both represent the degree and location of broken wires inside a cable was put forward. The training and predicting results of the sample database by the back propagation （BP） neural network showed that the proposed broken wires diagnosis method was feasible and expanded the broken wires diagnosis research area by using the smart cable which was used to be only representing cable force.

关键词： Fiber optical Bragg grating sensor bridge cable broken wires diagnosis smart cable BP neuralnetwork

Applying machine learning to study fluid mechanics

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Acta Mechanica Sinica 2021年第12期37卷 1718-1726页

作者： Steven L.Brunton Department of Mechanical Engineering University of WashingtonSeattleWA 98195USA

This paper provides a short overview of how to use machine learning to build data-driven models in fluid *** process of machine learning is broken down into five stages:(1)formulating a problem to model,(2)collecting and curating training data to inform the model,(3)choosing an architecture with which to represent themodel,(4)designing a loss function to assess the performance of the model,and(5)selecting and implementing an optimization algorithm to train the *** each stage,we discuss how prior physical knowledge may be embedding into the process,with specific examples from the field of fluid mechanics.

关键词： Machine learning Fluid mechanics Physics-informed machine learning Neural networks Deep learning

Long-Term Mechanical Properties of Smart Cable Based on FBG Desensitized Encapsulation Sensors

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Photonic Sensors 2014年第3期4卷 236-241页

作者： Sheng LI Min ZHOU National Engineering Laboratory for Fiber Optic Sensing Technology Wuhan University of Technology Wuhan430070 China Wuhan WUTOS Limited Company Wuhan 430223 China

In order to ensure the testing range and long-term reliability of the fiber Bragg grating （FBG） used for the smart cable, a smart cable embedded with FBG strain sensors based on the desensitized encapsulation structure was designed. For a smart cable specimen, the fatigue loading experiments with the cycle from 100 thousands to 2 million and 0.95 times nominal breaking cable force （Pb） were carried out, which tested the long-serving effects of the smart cable. The test results of the static tension loading and unloading during the stepwise fatigue cycle process showed that the encapsulated FBG strain sensors had the good linearity and repeatability. Also all sensors survived after 2 million times fatigue cycle. 0.95Pb static tension test showed that the encapsulated FBG strain sensors embedded inside the cable reached 4.5% testing accuracy in the 0.86Pb working range. After 0.95Pb static tension test, the dissection test was carried out by breaking the force tension. The results showed that the appearances of the encapsulated sensors were good, and the design structures were not changed and damaged.

关键词： Smart cable fatigue experiment fiber Bragg grating force monitoring bridge engineering

Wide Absorption Spectrum Measuring Methods by DFB-LDs in Water Vapor Detection System

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Photonic Sensors 2014年第3期4卷 230-235页

作者： Y. N. LIU J. CHANG J. LIAN Q. WANG G. P. LV W. J. WANG Z. LIU X. Z. LIU S. S. ZHANG Z. L. WANG S. JIANG C. G. ZHU W. WEI B.N. SUN School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology andApplication Shandong University Jinan 250100 China Institute of Automation Shandong Academy of Sciences Jinan 250014 China

Two measuring methods of the wide absorption spectrum by distributed feedback laser diodes （DFB-LDs） are presented in detecting the water vapor absorption line. One is the subsection scanning method, and it takes advantage of the wide spectrum tuning range by the temperature modulation and fast spectrum tuning speed by current modulation. Specifically, this method is realized by dividing a target spectral region into several sections which correspond to the specific temperature of DFB-LD, scanning every section by current modulation for hundreds times, and averaging the data to raise the signal to noise ratio （SNR）, then combining all sections to get the whole spectrum. An accuracy of 10ppmv had been obtained in the measurement of water vapor with a 10-cm path length by this method. Another is data fitting method, based on the absorption line-shape function; the absorption line can be described by fitting with partial measured data. The fitting absorption line was fitted well with the measured data, and the square of correlation coefficient （R-square） was no less than 0.99.

关键词： DFB-LD wide spectrum subsection scanning data fitting water vapor detection

Tilt Sensor Based on Intermodal Photonic Crystal Fiber Interferometer

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Photonic Sensors 2014年第3期4卷 209-214页

作者： Xiaotong ZHANG Kai NI Chunliu ZHAO Manping YE Yongxing JIN Institute of Optoelectronic Technology China Jiliang University Hangzhou 310018 China

A tilt sensor based on an intermodal photonic crystal fiber （PCF） interferometer is demonstrated. The sensor consists of a tubular filled with NaC1 aqueous solutions and an intermodal PCF interferometer, which is formed by using a short PCF with two single-mode fibers （SMFs） spliced at both ends, and the air-holes in the splice regions are fully collapsed. The intermodal PCF interferometer is fixed in a rigid glass tubular with a slant orientation, and a half of the PCF is immersed in the NaC1 aqueous solutions, while the other half is exposed in air. When tilting the tubular, the length of the PCF immersed changes so that the transmission spectrum moves. Therefore, by monitoring the wavelength shift, the tilt angle can be achieved. In the experiment, a 0.8-cm-length intermodal PCF interferometer was adopted. The sensitivity of the proposed sensor was obtained from - 1.5461 nm/° to -30.1244 nm/° when measuring from -35.1 ° to 37.05°.

关键词： Tilt sensors photonic crystal fiber interferometer intermodal