Research Of Distributed Fiber Optic Cable Detection System Based On The Structure Of Mach-Zehnder

Fiber optic sensing technology,a new sensing technology rapidly developed in the late1970swith the development of optical fiber and fiber optic communication technology, represents thedevelopment direction of a new generation of sensing technology.It has the characteristics of opticalfiber and optical measurement as well as many outstanding advantages, such as good electricalinsulation performance, strong anti-electromagnetism disturbance ability, high sensitivity, bigdynamic range, wide working band width and easy realization of remote monitoring of signalsmeasured; therefore, it has incomparable advantages comparing with traditional electronic sensingtechnology. Distributed fiber optic sensing realizes no "blind area" during the measurement andfundamentally breaks through the traditional single-point measurement limits, it’s a combination ofsensing and transmission, it can realize long-distance and wide-range measurement and monitoring,and can obtain the information changes on space and time measured along the fiber optic. Distributedfiber optic sensing technology is based on various modulation forms, such as strength, phase,frequency and polarization state, of which the sensitivity of distributed fiber optic sensors based onphase modulation form is higher. Phase modulation type of distributed fiber optic sensors can realizecontinuous high-precision measurement and location, and has broad application prospect. This paperresearches and discusses phase modulation type of distributed fiber optic sensors from two aspects,theory and experiment, and realizes signal processing as well as the operation and control functionsrelated to the system based on this. The research work of the whole article mainly includes:Firstly, it analyzes and introduces the current study situations of distributed fiber optic sensingtechnology at home and abroad and several kinds of common distributed fiber optic sensingtechnology, and it describes the composition and working principles of distributed fiber optic sensingsystem.Secondly, it mainly analyzes the theory and principle of distributed fiber optic sensing systembased on the interference effects, analyzes from elastic optics, phase modulation, and so on, andstudies the optical loop positioning principle based on Mach-Zehnder structure as wellascross-correlation algorithm used fortime difference measurement so as to provide theoreticalfoundation for the study of this paper.Thirdly, it designs the data acquisition and control system on the basis of LabVIEW according tothe research content of this paper, completes the compiling of man-machine interactive interface and data acquisition program, and achieves the acquisition, display and storage functions of the detectionsignals from distributed fiber optic sensing system studied in this paper.Finally, it carries out experimental analysis on distributed fiber optic detection system based onMach-Zehnder structure, and studies the detection and localization of disturbance in the test systemthrough the analysis and processing of signals collected. At the same time, it applies the system to thesafety monitoring of pipelines and the detection and researches of submarine optical cable injuries.