Research On Fiber Bragg Grating (FBG) Sensing Demodulation Systems

Sensing technology is one hotspot of the world’s high-tech, which is an important symbol of today’s scientific and technological development. Sensor technology,computer technology, and communication technology have formed the three pillars of the information industry.With the rapid development of fiber grating sensing technology, fiber grating sensing technology has been widely used in the field of civil engineering, aerospace, medical, power industry, petrochemical industry and others. Fiber Bragg grating (FBG) sensing technology not only has advantages of a low insertion loss, reflection narrow bandwidth, high temperature resistance, corrosion resistance, anti-electromagnetic interference, but also can use a variety of multiplexed mode to set up large-capacity distributed sensor networks easily, so distributed large capacity sensing system make high demands on sensitivity and stability of fiber grating demodulation system.This paper relies on a joint project called "fiber grating sensing system", which is between Beijing Jiaotong University and CSR Qingdao Sifang Locomotive Co., Ltd and elaborate the basic principles of FBG sensing focusing on fiber grating sensor demodulation system, including comparative study of five commonly used demodulation schemes, light source technology, tunable F-P filter, etalon research components etc..On this basis, dual-channel fiber Bragg grating sensor demodulation scheme based on tunable F-P filter was proposed and designed. The program analyzes the demodulation principle and introduced some devices chosen for the system,such as the ASE broadband light source, tunable F-P filter and optical receiver circuits. Finally, the dual-channel fiber Bragg grating sensor demodulation system based on tunable F-P filter was testd on railway locomotives in term of temperature, from which the results certify that the system has high sensitivity; chosing a self-designed double-ended surface-mounted FBG temperature sensor, which is stable and easy to install. Test results show that the dual-channel demodulation system based on F-P tunable filter possess high sensitivity, which the wavelength sensitivity is lpm,temperature sensitivity reachs at0.1℃,Success in achieving the designing objectives.