How Underground Fiber Optics Turn Your City Into a Living Intrusion Sensor
Every city sits on a mesh of underground fiber optic cables—installed for telecom, but capable of much more. A growing number of intrusion detection teams are learning to repurpose that existing infrastructure as a distributed vibration sensor. The technique is called distributed acoustic sensing (DAS), and it turns a standard fiber into a continuous array of virtual microphones. When someone digs, walks, or drives near the buried cable, the fiber's backscatter pattern changes, and you can pinpoint the disturbance with meter-level accuracy. This article is for security engineers, physical security managers, and SOC analysts who already know the basics of perimeter detection and want to evaluate whether fiber-optic sensing makes sense for their environment. We will skip the beginner primer on how fiber works and go straight to the trade-offs practitioners care about: installation gotchas, false alarm management, signal processing choices, and integration with existing alarm systems. 1.