光子学报, 2016, 45 (5): 0506001, 网络出版: 2016-06-06
一种多模FP激光器BOTDR系统的建模分析
Modeling Analysis and Calculation of a Brillouin Optical Time Domain Reflectometer System Using Multi Longitudinal Mode FP Laser
光纤光学 光纤传感 自外差检测 多模FP激光器 布里渊光时域反射计系统 信噪比 Fiber optics Optical fiber sensing Self-heterodyne detection Multi-longitudinal mode FP laser Brillouin optical time domain reflectometer Signal to noise ratio
摘要
根据相干检测理论提出了一种基于多模法布里-珀罗激光器的光纤瑞利与布里渊散射自外差检测的布里渊光时域反射计传感系统, 分析了该系统提高光纤受激布里渊散射阈值和瑞利与布里渊散射自外差检测的原理, 推导出系统信噪比表达式, 分析了纵模数与布里渊谱峰值功率、谱宽和系统信噪比、温度及应变测量准确度之间的关系, 并进行了计算.结果表明, 选用纵模间隔为0.141 nm的多模法布里-珀罗激光器时, 随着纵模数的增加, 在25 km光纤末端系统信噪比、温度和应变测量准确度均得到了较大提升, 当纵模数为19时, 温度和应变测量准确度分别达到最佳值3.81 ℃和86.69με.
Abstract
By using the theory of coherent detection, a Brillouin optical time domain reflectometer sensing system was proposed based on the external modulation of multi-longitudinal mode Fabry-Perot laser and the self-heterodyne detection of Rayleigh and Brillouin scattering. The principles of the stimulated Brillouin scattering threshold improvement by the utilization of the multi-longitudinal mode Fabry-Perot laser, the self-heterodyne detection of Rayleigh and Brillouin scattering were analyzed, the expression of signal-to-noise ratio of the system was deduced, and the longitudinal mode number dependences of peak power and bandwidth of superposed Brillouin spectrum, and signal to noise ratio, temperature and strain measurement accuracy of the system were analyzed and calculated. The results show that with the increasing of the longitudinal mode number, the signal to noise ratio, temperature and strain measurement accuracy of the system at the end of 25 km long fiber are improved significantly for a multi-longitudinal mode Fabry-Perot laser with a mode interval of 0.141 nm, and the optimal value of temperature and strain measurement accuracy is 3.81 ℃ and 86.69 με respectively, when the longitudinal mode number takes the number of 19.
李永倩, 曹翠新, 李晓娟, 安琪. 一种多模FP激光器BOTDR系统的建模分析[J]. 光子学报, 2016, 45(5): 0506001. LI Yong-qian, CAO Cui-xin, LI Xiao-juan, AN Qi. Modeling Analysis and Calculation of a Brillouin Optical Time Domain Reflectometer System Using Multi Longitudinal Mode FP Laser[J]. ACTA PHOTONICA SINICA, 2016, 45(5): 0506001.