The Study Of Botdr Distributed Optical Fiber Temperature Sensor Performance Improvement Methods

Because of the characteristics that it can obtain the continuous distribution of thetemperature information of the long distance sensing fiber on space and time, more andmore people pay attention to the distributed optical fiber sensing system based onBrillouin Optical Time Domain Reflectometry in recent years. This paper studied theimprovement of the temperature resolution and the time response speed of BOTDRtemperature sensor system. The specific research contents are as follows:Firstly, this paper elaborated the source of subject, background, research purpose andthe research status including domestic and overseas, then analyzed the present existingproblems of BOTDR system.Secondly, this paper analyzed the sensing principle of BOTDR system: including thescattering principle in optical fiber, the generation mechanism of Brillouin scattering, theprinciple of OTDR optical fiber sensing technology and signal detection technique ofBOTDR system. Then BOTDR sensing system is built on the basis of the aboveresearches, and the temperature sensing experiment is completed preliminary.Thirdly, this paper explored the improvement of the temperature resolution ofBOTDR system based on microwave electro-optic modulation, and analyzed the reason oftemperature measurement inaccuracy caused by BOTDR system reference beaminstability is analyzed in detail. Therefore, a method based on the output light powerfeedback of electro-optic modulator which can adjust the microwave power has beenproposed, it will keep the power of reference light of Brillouin optical time domainreflectometry stable. The experimental results show that this method can suppress thefluctuation of the power of reference light exported from the electro-optic modulatoreffectively, and the accuracy of the temperature measurement has been increased from6℃to2℃.Finally, this paper studied the improvement of the time response speed of BOTDRtemperature sensor system, and the real-time spectrum analysis technology based on fastFourier Transform is proposed. Then analyzed the principle of real-time spectrum analysis technology, and carried on the simulation of real-time spectrum of BOTDR systemsoftware based on Matlab. The simulation results show that this technology can effectivelyimprove the time response speed of BOTDR system.