Study And Design On Fiber Grating Sensor Matching Demodulation System

Fiber Bragg Grating (FBG) is a kind of fiber optic device which is expected to be of great prospect of application in fiber communication. Nowadays the manufacturing and application research on FBG has gone into a popular field of the fiber optics technology. As sensor, FBG can be immune from light source disturbance and system loss by transforming sensing information into its reflecting wavelength shift. Besides, FBG is very reliable and also immune from electromagnetic signals and corruption .Many FBGs can be put together on a single fiber to construct a FBG network to build a distributed sensing system. Such a system has shown the unexampled merit shift of Bragg reflecting wavelength precisely, and this is called demodulating of the coded wavelength signals. Though, the OSA can be used to do the measurement, it can not be applied to practical industry situation because of its huge-size and high-cost. Therefore, developing high-resolution and low-cost FBG demodulator is the key issue when it comes to FBG sensors industrializations. Although a large number of researchers in domestic research units have been done a lot of research and investigations on the demodulation of FBG sensor, most of the requirements of mass practical industrial productions.A new FBG demodulation scheme based on tuning matching fiber grating to interrogate the sensing grating is proposed in this paper. To achieve the demodulation of temperature and strain sensing signals, matching FBG's wavelength is changed by step motor which controlled by computer. Our main research work is as follows:The basic mechanism and main characteristic of fiber bragg grating are introduced. Fiber bragg grating sensor principle is researched in system. Compare and analyze fiber bragg grating demodulate programs in hand. In according with the problem in fiber bragg grating sensor practical application bring up new demodulate program: use matching fiber bragg grating demodulate program on the basis of cantilever demodulate sensor signal. Design and analyze the computer hardware of demodulate system. Using this program have finished physics stress sense demodulate experiment, analyse the result of experimentation, to test and verify the feasibility of fiber bragg grating demodulate program. Base on the result of experiment to sum up the advantage and disadvantage of this system and propose the improving method.