Phase unwrapping for fiber-optic distributed acoustic sensing

Abstract

Acoustic waves are observed as phase vibrations of Rayleigh backscattering in fiber-optic distributed acoustic sensing (DAS). In DAS, spatial derivative of phase represents the amplitude of an acoustic wave. Since measured phases are wrapped in (−π, π], phase unwrapping and differentiation are necessary to detect acoustic waves. In this paper, we propose a phaseunwrapping method in DAS using the Kalman filter and show that the acoustic waves are faithfully detected from noisy phase observation data.