Suppression of polarization sensitivity in BOTDA fiber distributed sensing system

Abstract

We propose and demonstrate a novel method to suppress the polarization induced signal fluctuation in Brillouin Optical Time Domain Analysis (BOTDA) fiber distributed sensing system. The polarization diversity scheme contains two polarization beam splitters (PBSs) and a piece of single mode fiber (SMF). The pulsed pump wave is split into two beams with orthogonal polarization states and one of the beams is delayed by a time related to the pulse width. Then, the two beams are recombined. Theoretically, the Degree-of-Polarization (DOP) of the recombined wave is zero and the distributed sensing system is insensitive to the polarization state of the probe. Stable distributed temperature measurement is demonstrated along a 1.2 km SMF.