Fiber Bragg Grating Sensor Demodulation System Design

This thesis presents my study efforts on new type of Fiber-Optic Sensors iber Optic Bragg Grating Sensor.Prime contents include development and product course of Fiber Bragg Grating(F5G), demodulation principles of F5G,design of demodulation system of Fiber Grating Sensors with a Cantilever Beam,analysis of experiments,and a mechanism based on fiber grating-pair is presented which is used to study the solution of cross-sensitivity of Fiber Grating Sensor measurement.On the basis of FBG' working mechanism which is expounded on the approach of Mode-Coupled theory,the paper analyzes and compares the characteristics of some typical demodulation mechanisms.A novel demodulation mechanism for FBG with a cantilever beam to linearly tunable filtering is designed, and the theoretical and experimental analysis on this demodulation mechanism is explained.Although the experiment conditions restrict it,the analysis of the measured data show the mechanism has great effect on the practical applicationjiot only in optical communication and sensor systems.In addition, put forward a sensing scheme and solution of cross-sensitivity of FBG measurements which uses the matching performance fiber grating-pair. The fiber grating-pair are respectively written on the opposite surfaces of the Cantilever Beam,and by measuring wavelength shift of the two peaks of FBG, strain and temperature can be determined simultaneously.Compared with some other schemes,the scheme uses only one set of laser-house and wavelength detection equipment,and the photic route gives more facilities for the practical application,and it's cost is cheaper. So this scheme shows some potentials of the practical application.In summary,the method and results described in this thesis are conducive to the advancement and applications of Fiber Grating Sensors and techique of tunable filtering with Cantilever Beam.