en.Wedoany.com Reported - Nokia has used optical tomography technology to transform a 2,000 km production fiber optic line into an active distributed sensor network. Developed by Nokia Bell Labs and validated in a live operational network environment in collaboration with Nordic research and education network operators CSC, Sikt, and SUNET, this technology has been successfully demonstrated.
In traditional network operations, operators struggle to monitor the physical status of fiber optic infrastructure in real time, often relying solely on basic continuity tests to determine if a line is broken. High-speed fiber optic networks are the invisible arteries of society, yet many operators do not actually own the external fiber segments they lease, which remain "black boxes" hiding security threats such as fiber tapping. Additionally, hidden risks like ship anchor dragging, construction excavation, or cable tension often go undetected until they cause connection outages, leading to costly emergency repairs.
Nokia Bell Labs' solution transforms passive glass fiber into distributed sensors through optical network tomography. Its core technology lies in analyzing minute changes in the polarization state of transmitted light. Vibrations, temperature changes, or mechanical stress can force light to deviate from its path, altering the polarization state. Research engineer Sylvain Almonacil stated that the team is not adding new sensors but rather converting the transponders already in the network into sensors, observing the system from within. The trial used Nokia's PSC 6S silicon engine, which features built-in advanced algorithms that continuously monitor polarization states, mapping physical stress on the cable in near real time without affecting data transmission speeds.
Coherent transceivers located at both ends of the fiber link serve as primary edge sensors, performing high-frequency measurements and collecting raw polarization data. The edge hardware feeds data to centralized processing algorithms that correlate minute changes recorded at both ends of the link, precisely locating the position and intensity of disturbances. This method enables end-to-end tracking of fiber segments spanning multiple operational domains, including those entirely managed by third-party telecom operators, thereby enhancing situational awareness and allowing administrators to accurately understand specific environmental vibrations and their geographic locations.
The trial network was based on SUNET's 2,000 km fiber infrastructure, carrying real traffic from universities and research institutions across the Nordic region. During three weeks of operational data validation, digital tomography estimates perfectly matched actual physical measurements obtained from the multi-domain network, successfully mapping all fiber types and precise span lengths along the entire line without interfering with primary customer data. Traditional methods for locating fiber breaks require days of work and significant capital expenditure, whereas the new technology narrows the search range from hundreds of kilometers to specific segments, enabling operators to intervene before physical damage occurs.
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