激光器线宽对-OTDR系统性能影响的研究

为了对相位敏感光时域反射系统进行优化设计,采用相位敏感光时域反射原理搭建了一套多点入侵检测系统,通过数值模拟和实验分析了激光器线宽对系统性能的影响,由理论分析发现,随着激光器线宽的增大,系统探测到的后向相干瑞利散射的波纹逐渐平滑,系统的信噪比和定位精度也随之降低,直至不能定位和识别干扰信息;并利用7km的光纤进行了相关实验。结果表明,当激光器线宽由5kHz增加到200kHz时,系统探测到的后向瑞利散射信号出现了较大的平滑,信噪比则由12dB减小到3dB,这与理论分析的规律一致。

Effect of laser linewidth on characteristics of -OTDR system

In order to optimize the phase sensitive optical time-domain reflectometer (-OTDR) system, a multi-intrusion detection system was built based on -OTDR principle. The effect of laser linewidth on system performance was studied theoretically and experimentally. 7km sensing optical fiber was used in system experiment. The theoretical analysis shows that with the increase of the laser linewidth, the ripples of backward coherent Rayleigh scattering detected by the system become gradually smooth, and the signal-to-noise ratio and location accuracy of system also decrease, so that the system can't locate and identify interference information. The experimental results show that when laser linewidth changes from 5kHz to 200kHz,the ripple of backward coherent Rayleigh scattering detected by the system also becomes gradually smooth, the signal to noise ratio of system decrease from 12dB to 3dB. The results of experiment is in agreement with the results of theoretical very well.