Exploration On Distributed Fiber Optic Temperature And Strain Sensing Using PM Fibers Based On Polarization Crosstalk Analysis

In this paper,we exploration on distributed fiber optic temperature and strain sensing based on polarization crosstalk analysis in the PM fibers,which have extremely broad application prospect.This paper mainly focuses on the relationship between the delay difference of PM fiber and the ambient temperature,the temperature sensing coefficient?TSC?measurement,the design and feasibility verification of distributed temperature sensing system,the relationship between the polarization crosstalk intensity and the stress on the PM fiber,axial strain measurement sensing baseband design,distributed axial strain sensor system design and feasibility verification and other aspects of research.Major innovations and contents of this dissertation:1.The theories of distributed optical fiber temperature sensing and distributed optical fiber strain sensing based on polarizations crosstalk analysis have been studied.The mathematical relationship between the delay difference of PM fiber and the ambient temperature,the mathematical relationship between the polarization crosstalk intensity and the stress on the PM fiber were deduced.The simulation analysis shows that there is a linear relationship between the stress and the polarization crosstalk intensity in a certain range.2.The TSC of the commercial fiber?YOFC PANDA_PM1550₁25-18/250?was measered as-0.7 ?m/?°C?m?by means of the method of making the preset crosstalk peaks at different intervals in the axial direction of the PM fiber.And two distributed temperature measurement schemes were designed.The feasibility of the distributed optical fiber temperature sensing system was verified experimentally for the first time.The measured spatial resolution of the sensing system is 1.42 m and the temperature resolution is 1.42 ? without considering the mechanical error of the PXA instrument.3.A novel PM fiber metal base band fabrication method was designed,which can effectively convert the axial strain of the fiber into transversal pressure,and a simple strain measurement system was built.This optical fiber strain sensing system achieved accurate distributed strain sensing in the range of 0 ?? to 160.888 ?? using a 5 m standard PM fiber.The feasibility of the distributed optical fiber strain sensing system by introducing the preset crosstalks was verified experimentally for the first time.And the spatial resolution of this system was as high as < 10 cm.