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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5k Hz增加到200k Hz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12d B减小到3d B,这与理论分析的规律一致。
In order to optimize phase-sensitive optical time-domain reflectometry system, a set of multi-point intrusion detection system is established by phase-sensitive optical time-domain reflectometry. The influence of laser linewidth on system performance is analyzed by numerical simulation and experiment. It is found that with the increase of laser linewidth, the ripple of the coherent Rayleigh scattering detected by the system is gradually smoothed, and the signal-noise ratio and positioning accuracy of the system are also reduced until the interference information can not be located and identified. The related experiments were carried out on the optical fiber. The results show that when the linewidth of laser is increased from 5k Hz to 200k Hz, the detected Rayleigh scattering signal is smoother and the SNR is reduced from 12d B to 3d B, which is in agreement with the theoretical analysis The same rule.