Performance analysis of distributed acoustic sensing systems based on Rayleigh-backscattering and wFBG-reflecting

A low-noise, low-calculation, long-range distributed acoustic sensing (DAS) system based on phase-sensitive optical time-domain reflectometry (Φ-OTDR) is proposed and analyzed. Based on this system, measurements were performed by using both Rayleigh backscattering light and wFBG-reflected light. An average phase noise of -47 dB can be achieved with wFBGs, which is about 15 dB lower than that with Rayleigh backscattering. The experimental results illustrate the potential for wFBGs in the proposed DAS system, which can demodulate external disturbance signal with good linearity and wide frequency response range, and immune to interference fading and polarization fading.