A long-range (124km) fully distributed fiber-optic vibration sensing system is demonstrated, based on phase-sensitive
optical time-domain reflectometry (Φ-OTDR) with counter-pumping distributed fiber Brillouin amplification (FBA).
FBA significantly enhances the probe pulse signal at the second half of the sensing fiber with less than 10dBm pump
power, and its amplification efficiency is demonstrated to be much higher than 26.9dBm counter-pumping Raman
amplification. As a result, demodulated intrusion signals along the whole sensing range can keep high signal to noise
ratio. The FBA scheme demonstrated in this work can also be incorporated in many other distributed fiber-optic sensing
systems for extension of sensing distance.