Research On A Simultaneous Measurement System Of Temperature And Strain Distribution Based On Brillouin Scattering In Optical Fiber

The research condition of Brillouin-based distributed optical fiber sensing technology is introduced in this thesis. The dependences of Brillouin shift and intensity on temperature and strain are investigated theoretically and experimentally. A Brillouin distributed sensing system for simultaneous temperature and strain measurement based on heterodyne detection is proposed and designed. The design considerations for optical transimit subsystem, optical receive subsystem and data processing subsystem are introduced in detail. Based on the performance measurement of electro-optical modulator (EOM) , the working parameters of the system are optimized. The measurements of optical time domain reflectometery waveforms along 10 km fiber are realized with a spatial resolution of 10 m. The system performance such as signal-to-noise ratio (SNR), temperature and strain resolution, dynamic range and measurement time are evaluated. The idea of applying Golay complementary sequences to Brillouin sensing system is presented, and the simulation results show that the SNR, temperature and strain resolution of the system are improved greatly by using Golay complementary sequences as the driving pulse of EOM and correlation detection.