Long-distance random fiber laser point sensing system incorporating active fiber

In this paper, we investigate the benefits of introducing the active fiber into long-distance point-sensing system based on random fiber laser (RFL). In this scheme the active fiber is placed between two segments of single mode fiber (SMF) and backward RFL pumping scheme is used. Through the numerical analysis, the influence of active fiber location on the spectral and power performance for the RFL is carefully discussed. Compared with the scheme without active fiber, the lasing threshold is much lower and the optical signal to noise ratio (OSNR) of the lasing line can be much higher, and the location of the active fiber has significant flexibility. The RFL experimental results are well coincident with the theoretical analysis; also, the sensing performance of such a system is demonstrated.