Fiber cable can actually be a very good sensor. Some light gets reflected back from the most minute bends of the cable. By sensing reflections and comparing them with previous reflections you can see whether the cable has experienced any new bends. By timing the arrival of reflections you can calculate exactly where the new bends are. By sensing the intensity of reflections you can calculate how sharp the bend is.

And this is not a research project anymore. Well, the fiber the article talks about is a research project, but there is a company called luna innovations that sells production fiber sensors that operate in commercial environments. There are underground fibers that sense whether someone steps in a restricted area. There are fibers stuck to pipelines that sense whether someone is trying to drill a hole in the pipeline to steal some oil (or any other vibrations or ruptures). There are fibers glued to the undersides of bridges that sense whether the bridge vibrates and bends too much.

It is a very useful sensor, because you can essentially get sensing along a large area without paying for multiple sensors and trying to figure out how you are going to power them, how they are going to communicate back, etc.

The electronics for extracting data from the fiber are complex but they do not have to be out in the wild in the area being sensed, they can be safely housed at one end of the fiber.