Research on Submarine Cable Anchor Damage Monitoring Technology Based on a Hybrid Brillouin and Rayleigh Distributed Sensing System

Submarine cables are critical infrastructure for global communication and energy transmission. However, they are susceptible to damage from anchors, fishing activities, and natural phenomena. This study developed and validated a hybrid Brillouin and Rayleigh distributed sensing system for monitoring submarine cable anchor damage. By integrating Brillouin Optical Time-Domain Analysis (BOTDA) and phase-sensitive optical time-domain reflectometry ($\Phi$-OTDR) technologies, we achieved high sensitivity and spatial resolution measurements of cable strain and vibration with a measurement length of 40 kilometers, a strain measurement variance accuracy of 0.65 $\mu\varepsilon$ and spatial resolution of 1m. Experimental results showed that the system could accurately detect and quantify cable strain and vibration responses caused by anchor impacts, hooking, and dragging events. Additionally, the vibration signals enabled tracking of the anchor's movement path. This hybrid monitoring method provides a reliable solution for real-time, precise detection of potential threats to submarine cables, enhancing their protection and reducing operational disruptions and maintenance costs.