Long-distance fiber bragg grating sensor system based on hybrid Raman/Erbium-Doped fiber amplification

In this paper, a hybrid Raman and Erbium-doped fiber amplifier (Raman/EDFA) is first proposed for enhancement of the performance of long-distance fiber Bragg grating (FBG) sensor systems. The Raman fiber amplifier is used for achieving low-noise amplification of FBG signals while the EDFA arranged remotely is used for both the compensation of the fiber loss due to long-distance transmission and the illumination of remotely-located FBG sensors as a broadband source by using the residual Raman pump power to generate ASE light and by amplifying the transmission light of the FBGs located before the EDFA. Such a sensor system adopts the advantages of the low noise feature of the distributed Raman amplifier and the high small-signal gain of the EDFA. Experimental results show that the performance of the sensor system has been improved significantly. A signal-to-noise ratio (SNR) of similar to 13dB has been achieved for a 50km transmission distance, which is similar to 10dB higher than that without amplification.