Practical Fiber Bragg Grating Sensors And Micro-structure Fiber Bragg Grating Sensors

This thesis focuses on the application of fiber Bragg grating (FBG) sensor and FBG sensing networks. The principles of the distributed fiber sensor and distributed FBG sensing technology are introduced. The FBG sensing technology, network multiplexing technology, and demodulation technology are mentioned in this dissertation. The FBG type and fabrication method have also been summarized. We have studied the application of FBG in temperature and strain sensing and highly precise and stable demodulation system. The experimental results are fairly good. The property of microstructure optic fiber (MOF)is researched in the thesis. We have analyzed and discussed the splicing loss between the MOF and the SMF, numerically simulated the fundamental and higher modes of the MOF, calculated the coupling wavelength of the MOF LPG(long-period grating) ,and utilized the MOF FBG in the field of fiber sensing.This thesis is supported by the national 973 project and key program sponsored by Tianjin science and technology committee. In this thesis, we have studied the FBG sensor used in the distributed FBG sensing demodulation system, FBG sensing networks based on the FP demodulation technology and MOF & MOF FBG. The main contents of the paper are listed as follows:1. The general development situation of the distributed fiber sensing technology, the distributed FBG sensing technology and the advantages of the distributed FBG sensing technology are summarized at first. Then we introduce the principles of the FBG sensing, FBG classification and theoretical analyzing method of the MOF.2.Several theoretical analysis methods of fiber grating characteristics are presented, including the mode-coupling theory, transfer matrix method,multi-film method and Fourier transfer method. The spectra of the FBG and LPG have been analyzed by these methods. The multiplexing techniques and fiber grating demodulation methods are introduced in this dissertation.3.We have designed and made the FBG-based temperature and strain sensors. The sensing principle and packaging configuration of the sensors are demonstrated. By using the automatic temperature control system and the automatic data acquisition system, the data precision has been greatly enhanced. The experimental data processed with new method show a good linearity and repetition of the sensor. The R2 is high enough to meet the demand in practical applications.