Fading noise reduction utilizing multi-wavelength scheme in phase interrogation based phase-sensitive optical time domain reflectometry

In this paper, a novel approach is proposed for fading noise reduction in phase interrogation based phase-sensitive optical time domain reflectometry (Φ-OTDR), which utilizes multi-wavelength optical pulses as the probe. Theoretical analysis is performed on the interference signal that is comprised of two Rayleigh backscattered light-waves (RBL) with a spatial shift along the sensing fiber. The theoretical analysis reveals that the magnitude of the interference signal is wavelength dependence. The wavelength dependence of the magnitude allows the novel approach to reduce the fading noise, which is confirmed by the well agreement of experimental results.