Multi-span optical fiber das system with dispersion management and staggered sensing pulses

Abstract

An undersea sensing system may include a first distributed acoustic sensing (DAS) station, comprising a first DAS transmitter and a first DAS receiver connected by an undersea optical communications cable. The first DAS transmitter is configured to launch a first outbound DAS signal in a first direction, over at least one sensing span of the optical communications cable. The DAS receiver is configured to receive a backscattered Rayleigh signal, based upon the first outbound DAS signal, wherein the first DAS signal is transmitted over a first D− fiber in a first half of the sensing span, and is transmitted over a first D+ fiber over a second half of the sensing span. The system further includes a second DAS station having a second DAS transmitter to launch a second outbound DAS signal in a second direction, opposite the first direction, over the at least one span. A second DAS receiver receives a second backscattered Rayleigh signal, based upon the second outbound DAS signal, wherein the second DAS signal is transmitted over a second D− fiber in the second half of the sensing span and is transmitted over a second D+ fiber over the first half of the sensing span.