Simulation Analysis On The Performance Of Distributed Fiber System Based On Stimulated Brillouin Scattering

Distributed optical fiber sensing technology with the ability of long distance sensing, wide range monitoring, resistance to electro-magnetic interference and many other advantages is currently a hot research topic in sensing research field, showing very broad market prospects. Distributed fiber sensing technology based on stimulated brillouin scattering as a kind of distributed optical fiber sensing technologies can realize the real time and continuous distributed sensing in detecting temperature and strain with a higher detection accuracy and system spatial resolution than tradition sensing technologies. We will present a numerical simulation research on stimulated brillouin scattering optical time domain analysis (Brillouin Optical Time-Domain Analysis, BOTDA) distributed optical fiber sensor system in this thesis:We will describe the characteristics of several distributed sensing technologies based on brillouin scattering based in detail, and give a detailed elaboration on BOTDA system's research and development status at home and abroad.Modified steady-state stimulated brillouin model is derived. The physical principles of optical time domain analysis distributed sensing system based on stimulated Brillouin scattering realizes temperature and strain sensing are described, The numerical relationship between temperature and strain and the Brillouin frequency shift and optical power is given.We study several key elements in the BOTDA system, do a comprehensive introduction and detailed analysis on the BOTDA dual light source and single light source architecture, several methods of the stimulated brillouin spectrum detection, the impact of polarization state on stimulated brillouin scattering as well as Pulse width's influence on spatial resolution of the system.The harmonics reconstruction algorithm based on original stimulated brillouin steady-state model can be applied to restore the temperature information and reduce errors. However, this model does not take into account of the fluctuated thermal noise's effects the numerical simulation in fiber. So we switched to use the harmonics reconstruction algorithm based on modified stimulated brillouin steady-state model, adding the fluctuated thermal noise coefficient B's effect to numerical simulation, and the noise factor B are related to the brillouin frequency shift and the fiber length. The the temperature peak errors of simulation results are closed to the experimental errors, proving that the noise factor B has a great impact on the system error, so the noise factor B can not be ignored and the application of modified model can make the simulation results match real situation. For multi-zone temperature distribution situation and the impact of extinction ratio, the simulation results are also presented and discussed.