Development Of Fiber Bragg Grating On Phase Masking In High Temperature

Fiber Bragg Grating(FBG)uses optical signals to collect,transmit,communicate and sense signals.It is inherently safe and immune to electromagnetic interference.At the same time because of its small size,long distance transmission advantages,it has been widely used in many areas of remote temperature sensing system.However,there is a significant degradation of FBG in high temperature environment.Degradation not only leads to "instability" of FBG sensing,sharp drop of sensing precision,but also seriously affects the sensing life of FBG sensor.Finally,it can not meet the long-term stable sensing requirement in engineering monitoring.Under the premise of ensuring the high sensing accuracy and sensing stability,how to improve the sensing life of FBG in high temperature environment is the key point for producing high temperature FBG.In this paper,the regression model of FBG in high temperature environment is firstly s?mmarized and the lifetime model of molecular structure is proposed to explain the decay phenomenon of high temperature FBG.The relationship between the decay process and the temperature and the time of use is obtained.Based on the life model,we select the appropriate high temperature fiber and,in accordance with phase mask FBG production process,optimize the high temperature FBG production process.Subsequently,we conducted temperature erosion experiments and temperature sensing experiments on the optimized high-temperature FBG to test parameters such as linearity,sensitivity,hysteresis and repeatability.After that,the production process can be further optimized based on the test results.In accordance with the established process of high temperature FBG applied to the blast furnace temperature monitoring,the effect is good.The high temperature FBG has not only the advantages of high sensing precision and stable temperature sensing,but also a stable sensing life of about 1.92 years when the reflectivity dropped from 5dB to 3dB under the environment of 350? and about 6.79 years when the reflectivity dropped from 5dB to 0.97 dB.Therefore high temperature FBG using phase mask production process has reached the needs of small batch production in the laboratory,of which not only the service life is relatively long,but the production cycle is relatively short.