基于Sagnac组合型干涉仪的光纤分布式扰动传感器

提出并研究了基于Sagnac组合型干涉仪的光纤分布式扰动传感器。扰动作用在传感光纤上引起传输光波相位的变化,可以通过Sagnac干涉仪进行检测。所提出的光纤传感器包括三个Sagnac干涉仪,它们共用一个宽带光源(BBS),并通过两个光电探测器(PD)检测干涉信号。由于宽谱光源的相干长度很短,因此只有经历相同路径的两束光会发生干涉,这样的路径存在三条。其中一个光电探测器检测有着相同环路长度的两个Sagnac干涉仪的信号之和,另一个光电探测器检测由法拉第旋光镜和传感光纤组成的干涉仪中的干涉光强。通过对探测器接收到的信号进行数学运算可以对扰动进行定位。实验结果表明,所提出的传感器可以检测并定位扰动。10次实验的最大定位误差为370 m,平均定位误差为270 m。

Fiber-optic distributed disturbance sensor based on merged Sagnac interferometers

The fiber-optic distributed disturbance sensor(FDDS) based on merged Sagnac interferometers is proposed and investigated. The disturbance causes a phase modulation and can be detected by the Sagnac interferometer. The proposed sensor includes three Sagnac interferometers merged sharing one broad-band source(BBS). The interference signal is acquired by two photo detectors(PDs) respectively. Since the coherent length of the source is too short for the lightwave propagating along different optical paths to interfere, there are only three paths of the light can interfere. One of the PDs detects the summation of the signals from two Sagnac interferometers which have the same loop length. The other PD measures the interference lightwave from the interferometer comprise of the Faraday rotator mirror (FRM) and the sensing fibers. The disturbance can be located by conducting mathematical operations to the detected signals. The experimental results show that the proposed sensor can locate the disturbance. The maximum location error is 370 m and the average location error is 270 m during 10 times experiments.