123 km Φ-OTDR System Based on Bidirectional Erbium-Doped Fiber Amplifier

摘要

Based on bidirectional Erbium-doped fiber amplifier (B-EDFA), which can amplify not only forward pulse light but also backward Rayleigh scattering light, a long distance (123 km) Φ-OTDR system is demonstrate. In this system, four B-EDFAs are employed to extend sensing length. Meanwhile, by using the difference value of upper-envelope and lower-envelope of Rayleigh scattering trace, the intrusion with SNR of 5.45 dB、 3.64 dB and 4.51 dB at three test points of sensing fiber is extracted.