Enhanced hybrid distributed multi-parameter fiber sensing based on distributed Brillouin amplification

In this paper, we propose and experimentally demonstrate an enhanced hybrid distributed multi-parameter fiber sensing based on distributed Brillouin amplification. By utilizing a continuous optical chirp chain (OCC) as a Brillouin pump, the power of the probe pulse can be amplified uniformly, thus improving the signal-to-noise ratio (SNR) of Rayleigh backscattering at the end of the fiber. Meanwhile, the temperature information can be extracted from the Brillouin loss spectra of OCC. In the experiment, OCC with a 60 ns segment duration and a 250 MHz sweeping range is employed. Benefiting from the Brillouin loss scheme, the SNR of phase-sensitive optical time-domain reflectometry (φ-OTDR) at the end of the fiber can be enhanced by approximately 10 dB. Distributed acoustic and temperature sensing is achieved with a strain sensitivity of 64 pε/Hz^1/2, a temperature precision of 0.2 ℃, and a spatial resolution of 6 m over 50 km single-mode fiber.