White-light Interferometry Sensor Based On Polarization Maintaining Fiber

In recent years,with the continuous improvement of the manufacturing process,the performance of polarization maintaining fiber(PMF)continues to improve.In addition to coherent optical fiber communications and fiber optic gyro,the polarization maintaining fiber are used in the field of fiber sensors more frequently.As an effective method of absolute measurement,which the traditional fiber optic interferometer used high coherent light source can not solve,fiber-optic white light interferometry technique has been widely used.In this paper,combining with polarization maintaining fiber and fiber optic white-light interferometry technology,we study the white-light interferometry stress sensor and temperature sensor based on polarization maintaining fiber.In the basic theory polarization maintaining fiber and white light interferometry,we analyze the principle of the polarization maintaining fiber to achieve polarization maintaining transmission,and then introduces the basic principles of fiber optic white light interferometry.The simulation of the optical fiber white light interferometry interference pattern is completed.Then we describes the basic structure of white-light interferometer and the related testing experiment.In aspect of white-light interferometry sensors based on optical fiber polarization coupling,the model of polarization maintaining fiber under stress is presented,and the influence of stress magnitude,direction and action length of PMF on the coupling intensity is analyzed.From the result of simulation,we get the relationship between stress factors and the coupling intensity,such as the stress magnitude,length and direction.With a single coupling point,we describes the principle of fiber stress sensor using PMF,and the method to calculate the coupling point location and intensity.We complete the relevant sensing experiment,and achieve quasi-distributed temperature measurement and distributed stress measurement.In aspect of white-light interferometry sensors based on polarization maintaining fiber gratings,we introduce demodulation principle using fiber-optic white-light interferometer,and simulate a white-light source interference pattern shaped by fiber gratings,then the relationship between the beatlength and the wavelength difference of two bragg gratings.At last,we completed the single-point temperature sensing experiment,and achieve thetemperature measurement of single-point.