Research On Brillouin Optical Time Domain Reflector System Based On Raman Amplification

The sensor based on Brillouin optical time domain reflector is one of thedistributed optical fibre sensor,which can measure both termperature and strainsimultaneously along the sensing fibre on the space and time and have the followingcharacteristics,the simplicity and convenience. In BOTDR system, the Brillouinscattering signal is so weak that the sensing distance is usually limited. Then thesignal-to-noise ratio and measurement precision are influenced in system. Therefore,the research on Brillouin optical time domain reflector system based on Ramanamplification is proposed.Firstly,the paper summaries the study status on the Brillouin fibre distributedsensors at home and abroad.The distributed sensors based on Rayleigh scattering、Raman scattering、Brillouin scattering principle is introduced in detail,including thedetection method for the weak spontaneous Brillouin signal and the influence factorsof BOTDR system,which laid a foundation for designing the whole system.Secondly, the paper studys the Raman fibre amplifier in detail and introduces thestructure of Raman laser and its operating principle.Next expounds the principle ofRaman amplifier.Then measures the gain figure and noise figure of Raman fibreamplifier according to the principle of Raman amplifier. Finally, the best Raman pumpwavelength is analysed by simulation.Then observes stimulated Brillouin scattering under the forward and backwardRaman pump by experiments,and compares the effects of the forward and backwardRaman amplification.The Raman pump configurations are achieved for BOTDRsystem by analyzing backscattering light of distributed Raman amplification.Finally, many experimental results verify the feasibility of the Brillouin opticalreflector system based on Raman amplification.And then proposes and analyses theperformance parameters of BOTDR system,next verifies the feasibility of this systemby experiments,and measures the fibre temperature by tests.