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Study On Distributed Optical Fiber Vibration Sensing Based On Polarization Detection

Posted on:2013-02-24Degree:MasterType:Thesis
Country:ChinaCandidate:J LiuFull Text:PDF
GTID:2218330362461821Subject:Information and Communication Engineering
Abstract/Summary:PDF Full Text Request
Optical fiber sensor is gradually accompanied by the development of optical communication technology. It integrates information collection and transmission in one optical fiber. Its advantages of high sensitivity, long distance monitoring and accurate location have been discussed a lot. It provides the availability of intruder detection, early warning and location in the pipeline security monitoring system.This paper analyzes the typical characteristics of the threats to the pipeline safety, presents a new type of distributed optical fiber vibration sensing system based on polarization detection. By employing a Faraday rotator mirror (FRM), the sensor only responses to the change of transmission light's polarization caused by rapid vibration, and eliminates slow polarization change interference or random polarization drifting. Through analyzing the intensity of the reflected sensing light and the time information, it is able to locate and recover the vibration signal simultaneously. The operation performance of the proposed device is theoretically analyzed and experimentally demonstrated in this paper.The main work of this paper covers the following aspets:(1)A large number of relevant researches on the distributed fiber sensors is carefully studied. Compared with several common sensing technology based on the optical time-domain reflectometer(OTDR) and the interference structure, distributed optical fiber vibration sensing system based on polarization detection is proposed.(2)The hypocenter vibration model and earth vibration model are formed after analyzing the vibration signal feature aroud the pipeline.The evolution of polarization during the transmission is described by Jones matrix. According to the cross-power spectral density correlation analysis, the time delay between the vibration signal and the sensing signal is calculated to locate the disturbance point.(3) Based on the theoretical research, the experimental system is constructed by applying a voltage-controlled polarization controller to change the polarization of the transmission light as the interference. While rapping the steel pipeline to simulate the actual vibration.
Keywords/Search Tags:optical communication, distributed optical fiber sensing, polarization detection, polarizing beam splitter, Faraday mirror, time delay estimation, correlation analysis
PDF Full Text Request
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