基于3×3迈克耳孙干涉仪的四路检测相位解调Φ-OTDR  

Four-Channel Detecting Phase Demodulation Φ-OTDR Based on 3×3 Michelson Interferometer

作　　者：宋牟平[1] 尹聪[1] 陆燕[1] 朱伟基 吴媖 庄守望 Song Muping;Yin Cong;Lu Yan;Zhu Weiji;Wu Ying;Zhuang Shouwang(College of Information Science and Electronic Engineering,Zhejiang University,Hangzhou,Zhejiang 310027,China)

机构地区：[1]浙江大学信息与电子工程学院,浙江杭州310027

出　　处：《光学学报》2018年第8期278-283,共6页Acta Optica Sinica

摘　　要：相位敏感光时域反射计(Φ-OTDR)中使用相干性较好的窄线宽光源,因传感光纤中光脉冲产生的散射光发生干涉,故可利用干涉光的变化检测外界扰动,检测灵敏度较高。但传统的幅度检测Φ-OTDR的结果难以实现定量检测,需要进行相位解调。基于3×3迈克耳孙干涉仪的相位解调系统是一种较好的解调方案,但直接解调的结果存在空间分辨能力小于传统幅度检测Φ-OTDR的问题。采用四路检测方法来保持Φ-OTDR的空间分辨能力,只需在系统结构中增加一路检测。同时考虑到窄线宽光源产生的脉冲内干涉对解调造成的不利影响,在提出四路检测相位解调Φ-OTDR的基础上,从瑞利后向散射光的角度对基于3×3迈克耳孙干涉仪的相位解调Φ-OTDR进行分析,并通过实验进行验证。完成了对5km传感光纤上扰动信号的定量检测,检测线性度为0.9956,解调相位的幅度达到31.85rad,解调系统的空间分辨率与传统的幅度检测Φ-OTDR相同。Phase-sensitive optical time domain reflectometry（Φ-OTDR）uses narrow line-width laser with high coherence.In the sensing fiber,scattered lights from optical pulse interfere,and the interference light is highly sensitive to external disturbance.But the traditional amplitude-detectionΦ-OTDR is not quantitative detection,so that phase demodulation is necessary.Phase demodulation system based on 3×3 Michelson interferometer is costeffective,but is of lower spatial resolution than the traditional amplitude-detectionΦ-OTDR.We propose a fourchannel detection method to preserve the same spatial resolution as amplitude-detection Φ-OTDR by adding only one detection channel.But the interference of scattered lights may have critical influence to phase demodulation.A fourchannel detection system of phase demodulationΦ-OTDR is analyzed based on 3×3 Michelson interferometer,from the aspect of Rayleigh backscattering light.The experiment shows that the disturbance around the fiber is detected quantitatively,with a linearity of 0.9956,phase sensing range of 31.85 rad,and the spatial resolution is same as that of amplitude-demodulation Φ-OTDR.

关 键 词：光纤光学 分布式光纤传感 相位敏感光时域反射计 相位解调 定量检测 四路检测 

分 类 号：TP212[自动化与计算机技术—检测技术与自动化装置]