When Fiber-Optic Cables Learn to Listen

Trial shows subsea cables can sense threats and guard themselves, changing Asia-Pacific network security.

7 Jul 2025

A month-long trial in the South China Sea has demonstrated that standard submarine fiber-optic cables can be adapted to act as real-time monitoring systems, potentially reshaping security for undersea networks in the Asia-Pacific.

Researchers converted a 29km section of cable at the Datang Offshore Wind Farm into more than 7,000 virtual sensors, able to detect movement, vibration and environmental changes without removing the infrastructure from the seabed. The project used distributed acoustic sensing, which sends light pulses through unused fiber strands and analyses the reflected signals to identify activity such as vessel movements, fishing operations and anchor drags.

The South China Sea Institute of Oceanology, working with Tongji University and the Guangdong Earthquake Agency, said the approach allowed operators to track both the cable’s condition and surrounding marine activity entirely from shore. “We can now give operators constant, accurate information about their cables without touching the infrastructure,” said a lead researcher involved in the initiative.

The method reduces the cost and downtime associated with conventional inspections and could be integrated into new systems from the outset. Industry analysts said that embedding such technology into the design of future high-capacity cables could make networks more resilient, speed up repair times and generate additional value by sharing environmental data with maritime authorities or research bodies.

The potential for commercial and scientific cooperation is significant, but challenges remain. These include managing the volume of data generated by thousands of virtual sensors and ensuring compliance with varying national and international rules on maritime surveillance.

Even so, sector specialists view the development as an early step towards “smart” subsea cables, critical infrastructure that not only carries global internet traffic but also monitors and safeguards itself. As more undersea routes are built to connect the Asia-Pacific, the South China Sea trial could prove a reference point for future projects.