Ultra-Long Distance Fiber Bragg Grating Sensor System

A novel tunable fiber ring laser configuration with a combination of Raman amplification and erbium-doped fiber amplification(EDFA) is proposed for realizing high signal-to-noise ratio(SNR),ultra-long distance(300 km) fiber Bragg grating(FBG) sensor systems.The hybrid Raman–EDF amplification configuration can enhance the optical SNR of FBG sensor signals significantly,so the optical power reflected by the fiber Bragg grating can be compensated.A good optical SNR of 15 dB is achieved for a 275 km transmission distance,which is the best performance to our knowledge,and about 4 dB at 300 km.In the static strain experiments with fiber lengths of 100,200,250,300 km,the linearity is greater than 0.999.This system can be widely used in the ultra-long-distance sensing applications such as railways,oil(gas) pipelines and coastline.