Distributed Sensing Of Optical Fiber Brillouin Scattering Based On Spread Spectrum Technology

In recent years,brillouin scattering has attracted more and more attention due to its long transmission distance and high precision.However,the optical signals will be limited in transmission and the transmission distance in system and its signal-to-noise ratio will be affected due to its extremely weak light.The brillouin system is optimized by spread spectrum technology and the transmission signal is demodulated by optical domain demodulation in this paper.The details are as follows:Firstly,the development of the distributed sensing technology is introduced.The current situation of the brillouin distributed sensing system based on spread spectrum technology is described.The principle and the performance of the spreading sequence are analyzed.The generation of the m-sequences in this system is described in detail.Secondly,the detection principle of the brillouin scattering is analyzed.The brillouin modulation system based on the spread spectrum technology is built.The brillouin coherent detection system is tested and the first-order edge wave is obtained.The modulation simulation system is built by Optisystem software and this system is proved to be feasible.The results of the experiment correspond to the simulation results,which verify the correctness of the system.Finally,the signal of the brillouin system based on the spread spectrum technology is demodulated by the optical domain demodulation.The simulation system of the optical domain demodulation is built.The experiment results prove that the optical domain demodulation can effectively reduce the requirement for hardware in electrical domain despreading.The probe points on the fiber are tested in the experiment system.Experiments were performed on 9.3m fiber and 1030 m fiber,respectively,and good resolution was obtained.An temperature experiment system of brillouin signal is built,the required temperature coefficient and better temperature accuracy is obtained.