白光干涉偏振模耦合分布式光纤传感器分析

分布式光纤传感器能够测量沿光纤长度上连续分布的外界量。用保偏光纤作为传感光纤的分布式光纤传感器，被测外界量引起保偏光纤中传播的两正交偏振模的相互耦合。用迈克尔逊干涉仪两臂光程差来补偿两个偏振模的光程差的方法探测传感信号。为了设计白光干涉偏振模耦合分布式传感器，根据统计光学原理分析了传感器的互相干特性。在此基础上分析了传感器的空间分辨力、光纤耦合点分辨力、最大传感光纤长度。波长1310nm、谱宽36nm的超辐射发光二极管(SLD)作光源．用色散参量为600ps／km，拍长3mm的保偏光纤的分布传感器空间分辨力和光纤耦合点分辨力分别为6cm和3mm。

Analysis of White-Light Interference Distributed Optic Fiber Sensor by Polarized Modes Coupling

The distributed optical fiber sensors can measure the environment factors which continuously distributed along a length of optical fiber. For a distributed fiber sensor taking a polarization-maintaining fiber as sensing fiber, the environment factors induce the orthogonal polarization modes propagated in the fiber coupling each other. The sensing signal is detected by means of compensating the optical path difference of the two orthogonal polarization modes by two arms path difference of Michelson interferometer. In order to design white light interference distributed optical fiber sensor by polarized modes coupling, the mutual coherent characteristics of the sensor were analyzed according to the principle of statistic optics. On these bases, the length resolution, fiber coupling point resolution and maximum sensing fiber spatial of the sensor were obtained. The length resolution and the coupling point resolution are 6 cm and 3 mm respectively for a distributed optical fiber sensor with a superradiant light-emitted diode(SLD) source of center wavelength 1310 nm, spectral width 36 nm and a polarization-maintaining fiber of polarization dispersion coefficient 600 ps/km and beat length 3 mm.