Disaggregated DAS interrogation for branched fiber networks

Distributed acousto-optic sensing (DAS) enables continuous, high-resolution acoustic monitoring over kilometer-scale distances using standard optical fibers. However, this sensing technique faces limits concerning loss, such as those inherent to passive optical networks (PON). The optical synchronization of remote DAS interrogators with centralized narrow-linewidth light sources that have been off-loaded from the field-distributed sensing units enables to probe the fiber plant of PONs from the branch-side of their power-splitting signal distribution elements. Towards that, acousto-optic acquisition is demonstrated for PON reaches of 14.1 km and large 1 × 128 split ratios.