Study On The Hydrogen Sensor Of LPFG

Concentration is important parameter of gas. It is important to measurement and control towards gas concentration in the areas of paper making, chemical, refine sugar, food, medicine and so on. Fiber grating has the advantages of electric insulation, resistance of the interference of electromagnetism,anti-crosion,smallvolume,light weight,high sensitivity,strong repetition and so on. It can fetch up the disadvantages in traditional measurement. Thus it is a promising sensor of solution concentration.This paper takes long period grating (LPFG) as the object. We study the theory of LPFG and sensing technique. We propose the measurement towards gas concentration. Finally we take an esperiment of LPFG sensing.The paper generally introduces the study of making and implication of fiber grating. We deduced the coupling coefficient. We study the effect of grating parameter on the spectrum. The formula of resonance peak shift is deduced. We have the sensing characters with different parameters of LPFG under the simulation using Matlab.The paper design a gas concentration sensing equipment using different LPFG, and different concentrations of a set of Hydrogen gas are measured experimentally. The relationships of LPFG of resonance wavelength and Hydrogen gas concentration can be deduced from experiment data and formula of LPFG refractive index sensing. And the result of the experiment for the Hydrogen gas is the same with the simulation using Matlab. At last,we descript the error of the experimental in detail .