Distributed Stress Sensor Based On Polarization Maintaining Fiber

Distributed optical fiber sensor is widely used in the field of long-haul intelligent controlling. In recent years, PMF based distributed optical fiber stress sensor has attached great interests due to its high measurement accuracy, large measurement range and simple structure. This thesis presents a PMF-based distributed stress sensor using pulse light source. This type of distributed stress sensor can measure the location and the intensity of stress simultaneously.The main contents of this article:First, we analysis the distributed fiber optic stress sensor system and the polarization maintaining fiber and its application in a distributed fiber optic stress senors, we also research their history and development.Second, we analyzed the principle of a polarization maintaining fiber, polarization maintaining and polarization coupling theory, deduced the mode coupling theory induced by stress perturbations in PMF, obtained the relationship between the output coupling ratio and the intensity of stress.Third, in the part of the experiment, we design a distributed stress sensor which using a PMF with a beat length of3mm. This distributed stress sensor measures the location and the intensity of stress through testing the polarization mode delay and coupling ratio, respectively. The simulation analyzed relationship among coupling ratio, the intensity of stress, stress length and stress angle. The experiments show that this distributed stress sensor can test a PMF with a length longer than1500m, has good repeatability and the sensitivity of the system is20uW.