Sensing Characteristic About Fiber Grating And It Is Applied In The Sensing Technolog

This paper mainly study on the theory of the mode coupling and the experiment of the temperature sensing.In the mode coupling , Based on the ideal approximation of the coupled-mode theory, the transverse component of the electrical field was regarded as the superposition of the non-perturbation some ideal modes , the periodic change of FBG's refractive index was regarded as the perturbation of the dielectric constant ,coupled-mode coefficient of the polarization current's conception was used, predigest the equation of coupled-mode ,solved the refractive index and the characteristic parameter expression of FBG's reflection wavelength ,the theoretical calculation results are coincident with the experimental results.In the temperature sensing, the theory of fiber Bragg grating(FBG) temperature sensing has first been proposed, the characteristic of the FBG temperature sensing was analyzed, it was deduced that the sensitivity coefficients of first-order and second-order ,and experimental findings was protracted, the gained polynomial better inosculate with the theory value. The experiment was processed in the low temperature , the thermo-optic coefficient was emended in the polynomial of the normal temperature ,the result was accorded with the sensing character of the normal and low temperature ,and it was resolved that the theory account of the normal and low temperature did not accord with the experiment.