Research On Hybrid Fiber Sensing Of FBG Interrogation And Spectrum Linewidth Measurement Based On Gas Absorption

Fiber Bragg Grating(FBG)sensor has the advantages of non-electromagnetic interference,passive,anti-corrosive and reusable,which can realize quasi-distributed measurement.It is very important to realize temperature monitoring in special environment such as flammable and explosive.The gas absorption lines have a good stability with the temperature change.It can be combined with the F-P etalon for wavelength reference in FBG interrogation to be more accurate.At the same time,the study found that the gas absorption linewidth and its temperature,pressure has an important relationship.In this paper,according to the fiber Bragg grating interrogation technology and gas absorption spectrum sensing technology,we have research on the temperature of the fiber grating interrogation and gas absorption linewidth measurement of hybrid sensing technology,which provides a useful exploration for optical fiber composite tester with larger capacity,multi-parameter,large scale and high measurement precision.The work done in this paper is as follows:1)A hybrid sensing system with fiber grating interrogation and spectral line width measurement is developed.The overall design of the hybrid sensing system is completed.The system optical path,power circuit and photoelectric detection circuit are built up.The whole instrument shares the same Distributed Feedback Laser,that is DFB,the gas absorption chamber and the same optical path structure.The FBG interrogation module and the line width measurement module work together to realize temperature monitoring and line width measurement.2)Based on the analysis of the temperature stability of the acetylene gas absorption chamber and F-P etalon,the peak-finding algorithm in the fiber grating interrogation is designed based on the gas absorption lines as the wavelength reference.We introduced the typical line width based on integral to achieve a stable line width measurement.3)The performance of hybrid test system in temperature detection and line width measurement is studied experimentally.The experimental results show that the FBG temperature interrogation module has a temperature measurement accuracy of <± 1 ?;the mean square error of the line width measurement is less than 0.6 pm,and the feasibility of its application in temperature sensing is discussed...