Extending dynamic acoustic sensing range and localization in undersea cables using loopbacks

A method, comprising:

• launching a DAS signal from a DAS interrogator over an outbound DAS signal path, comprising at least one optical fiber;
• amplifying the outbound DAS signal at a plurality of amplifiers along the outbound DAS signal path, the plurality of amplifiers being distributed over a plurality of spans;
• routing the outbound DAS signal into a plurality of loopbacks arranged between the outbound DAS signal path and a return DAS signal path;
• transmitting, along the return signal path, at least one return DAS signal from at least one loopback of the plurality of loopbacks to the DAS interrogator;
• and
• amplifying the at least one return DAS signal,
• wherein the at least one return DAS signal is processed by a component located at the at least one loopback to provide span-specific DAS information to the DAS interrogator.

A system comprising:

• a DAS interrogator to launch an outbound DAS signal;
• an outbound signal path for transmitting the outbound DAS signal over at least one outbound optical fiber;
• a plurality of outbound amplifiers, coupled along the outbound signal path, and separated from one another by a distance defining a span;
• a return signal path for conducting a plurality of return DAS signals based upon the outbound DAS signal, over a return optical fiber;
• a plurality of return amplifiers, coupled along the return signal path, and separated from one another by a distance defining a span;
• a plurality of loopbacks, to reroute the outbound DAS signal between the outbound signal path and the return signal path, to form the plurality of return DAS signals;
• a loopback component, arranged in at least one loopback of the plurality of loopbacks, to regulate transmission of a return DAS signal from the loopback to the DAS interrogator;
• and
• an optical amplifier, disposed in the at least one loopback.