Research On The Fiber Grating Based Measurement Of Temperature And Strain

The research condition of fiber Bragg grating (FBG) sensing technology is reviewed in this thesis. The dependences of FBG center wavelength on temperature, strain and pressure are investigated theoretically. A fiber Bragg grating sensing system based on tunable Fabry-Perot filter is proposed. The FBG sensing array is designed and the addressing of FBG array is achieved by calculating and wavelength encoding. The engineering structure for laying down the optical cable in ocean is presented based on the design of excess optical cable reel and optical cable fixing collar. The experiment system is constructed to measure the characteristics of temperature and strain of a single FBG and the FBG array. The experiment results show that the FBG center wavelength has good linearity and reproducibility with temperature and strain, respectively. In the range of -6 to 40℃, the temperature-sensitivity of packaged FBG by brass is 40.286 pm/℃that is about 3 times larger than that of unpackaged one. In the range of 0 to 700με, the strain-sensitivity of packaged FBG is 0.789 pm /με, a little smaller than that of unpackaged one. The FBG sensing array works well without cross-talk of reflecting spectra.