Based On Long-distance Sensing Systems And Applications Of Fbg

With the rapid development of the large buildings,the long-distance pipelines,railway,the oil and gas coal etc, the advanced research on long-distance sensor system for safety and health monitoring is particularly urgent.The medium of the long-distance optical fiber sensing system is optical fiber, the system can be divided into distributed sensing system and quasi-distributed sensing system. This course studies the quasi-distributed sensing system using optical Fiber Bragg Gratings (FBG) sensor to monitor electric safety and measure temperature (strain) with the sensing distance achieve to 300km.Firstly, this paper analyses the working principle,application and current situation of the development of the FBG sensing system, and then analyses the reuse of demodulation technology of FBG.. Next, we study the principle, advantages and disadvantage of various light amplification technology. We choose Erbium Doped Fiber Amplifier (EDFA) and Raman amplification technology applied in long-distance optical fiber sensing system according to the characteristic and actual needs.Then we built a long distance FBG sensing system and put forward FBG sensor (FBG) system which was based on the adjustable laser and acousto-optic pulse modulator(AOM), obviously improved FBG sensing system (FBG) using the combination of EDFA and Raman amplification, in the end we achieved the ultra-long distance sensor system.We designed and built a long distance quasi-distributed sensing system based on low reflectivity (each FBG reflectivity achieved to 5% of the FBG sensing system), used the time-division multiplexing based on the FBG, set multiple wavelength of the same low reflectivity FBG respectively in different position, constituted the distributed optical fiber sensing system in order to realize the sensing points of strain measurement. The use of EOM greatly reduced the cost of the system, the monitoring distance achieved 125 km, the linearity can achieve reached above 0.999 in its static strain experiment. The system had high accuracy and can monitor multiple points simultaneously. Finally, we designed and built the electric safety monitoring system based on the FBG sensors, using FBG strain and temperature characteristics, which was put forward to applied to wire transmission ice waved monitoring. We proposed package two FBG together and monitor the temperature and strain simultaneously and use special material to achieve monitoring special requirements.This system used the Wavelength Division Multiplex(WDM) FBG sensor network, the N FBG which had different wavelengths were placed along the optical fiber to monitor different areas to achieve the real-time and on-linemonitoring objects N.