Research Of A High-capacity Fiber Bragg Grating Sensing System

At present, the fiber grating sensor rapidly develops in the sensor area with its advantages of simple structure, anti-electromagnetic interference capability, some major projects and structure monitoring often requires a large number of sensors, therefore the study of a fiber-optic grating sensor system which can distributed measure and have long-term stability and high-capacity has great significance.The main works of this paper are as following:1) Existing fiber-optic grating sensor demodulation and multiplexing is analyzed and compared. A high-capacity fiber-optic grating sensor system is designed based on the the F-P tunable filter.2) In order to improve the capacity of sensing systems, optical fiber delay line is added in the system. Reflected signals in different paths are separated in the timing. Time-division multiplexing is achieved based on Wavelength-division multiplexing. The sensor with same center wavelength can used in different paths which aren't limited by the center wavelength. The number of FBG sensors is greatly increased.3) The fiber grating sensor demodulation system is set up using broadband light source, FP tunable filters, coupler, optical fiber delay line, signal detector and the DSP system, and debug to run stable.The specific optical system form is discussed, and the principles and characteristics of the device is introduced.4) The laboratory environment is monitored in long time useing the FBG sensor system.The result is compared with the the traditional thermometer's result,and the system can be stable and accurate. Experimental results show that the system can measure the temperature stably and accurately.