本文研究了布里渊回波分布式光纤传感系统的原理, 采用微扰法推导了瞬态受激布里渊散射(SBS)耦合波方程组, 求得了 SBS作用的瞬态解。利用 Matlab仿真研究了不同脉冲调制的布里渊光时域分析(BOTDA)系统中 SBS过程的布里渊增益曲线, 并对传感系统的三维增益谱进行了仿真与分析, 结果表明基于亮脉冲调制、暗脉冲调制、π-相位脉冲调制的 BOTDA系统具有高的布里渊增益和窄的布里渊线宽, 同时能够实现高的空间分辨率, 其中π-相位脉冲调制时可获得最大的布里渊增益。

The principle of distributed optical fiber sensing system based on Brillouin echo is analyzed, the transient coupled wave equation of Stimulated Brillouin Scattering (SBS) is deduced by a time domain perturbation method, and the transient solution of the SBS process is obtained. The Brillouin gain curves of the SBS process in Brillouin Optical Time Domain Analysis (BOTDA) systems using different pulse modulation are studied by Matlab simulation, and the 3-dimensional Brillouin gain spectra of the sensing systems are analyzed. The simulation results show that high Brillouin gain and narrow Brillouin linewidth as well as high spatial resolution can be achieved in BOTDA systems with bright pulse modulation, dark pulse modulation, and π-phase pulse modulation. And the largest Brillouin gain can be achieved in the π-phase modulation system.