Research On Wavelength Demodulating Technology Of Fiber Bragg Grating

Fiber grating Sensors are new type of passive optical components, which can be used to measure lots of physical parameters. As a new type of sensing technology, the fiber grating sensing technology has been caused extensively focus. FBG sensors have many inherent advantages over conventional electrical sensors such as non-conductivity, small size, light weight, fast response and resistance to corrosion. They provide absolute wavelength encoding that is independent of the overall system light levels but is dependent on the strain and temperature effects acting on the sensing elements. These types of sensor has strong capacity against electromagnetic interference, high sensitivity and stability, can be multiplexed. These advantages of FBG sensors make it develop quickly, and now have been successfully used in bridge construction, electric power monitoring, railway safety and many other fields.Theory and technology of fiber Bragg grating (FBG) sensor are systematically researched in this paper. The research includes: the coupled mode theory of fiber grating; the sensing mechanism of FBG; various methods of wavelength analysis; the design of FBG interrogate system based on tunable F-P filter; and the test of temperature and strain using FBG interrogate system. The main work of this paper is as follows:1. The relationships between the reflective spectrum characteristics of fiber Bragg gratings and their structural parameters are studied. FBG sensor formula was derived.2. Giving comparison of the existing FBG wavelength analysis technologies, selected method of F-P tunable filter. According to the shortcomings of existing methods, etalon filter and reference FBG are used in order to improve the accuracy of wavelength analysis system. Elaborate on the composition of the system, explains principles and performance of the components in light road, set up FBG wavelength analysis system.3. Experiments with the sensing system are described. Using FBG sensors with different package, Strain data of different steelworks are gathered and compared with theoretical values and traditional electrical sensors, the results verify the feasibility of FBG sensing system. are used in temperature measurement. Results are used in the testing of stability and accuracy of FBG wavelength analysis system we set up.