Exploiting optical fibres to monitor the environment and earthquakes: Unipd also in the project

Our planet is surrounded by a network of billions of kilometers of optical fiber, through which all the information that travels on the Internet is transmitted. Thanks to recent technological developments, the scientific community opens up a new opportunity in environmental monitoring: using existing fiber optic telecommunications networks as a system of environmental sensing distributed at a planetary level.

Transforming telecommunications networks into a globally distributed sensing system, with applications ranging from environmental surveillance (such as earthquake and tsunami tracking) to infrastructure monitoring and anomaly detection, is the goal of the Ecstatic project. However, this requires a review of the specifications of communication techniques, signal and device characteristics, as well as system designs and architectures, to realize the potential for use in other contexts, thus exploiting the considerable value derived from the significant costs of deploying the networks. Ecstatic, which has a duration of four years, has received funding of over four million euros from the European Union's Horizon Europe research and innovation program, and involves 14 European partners. Among them, the team from the Department of Information Engineering of the University of Padua, led by Professor Luca Palmieri, is developing an innovative system that will allow submarine fiber optic cables to be used as environmental sensors. The research activity, carried out in close collaboration with the University of L'Aquila and Sparkle, will culminate with an experiment on Sparkle's BlueMed cable, which runs from Genoa to Palermo across the Tyrrhenian Sea.

"Fiber optics - underlines Luca Palmieri, professor of Electromagnetic Fields and project manager for the University of Padua - are everywhere, even in the most inaccessible places, such as the bottom of seas and oceans, and are an excellent means of communication. However, receivers must constantly estimate and equalize the transmission channels to ensure that the Internet works regularly. In making this estimate, the receivers are also, indirectly, measuring the environment. From this consideration was born the idea of ​​using existing optical communication networks to detect earthquakes, tsunamis, anomalous vibrations of civil infrastructures, such as bridges and skyscrapers, but also roads and highways. Think, for example, of a train that passes over a bridge, where fiber optic cables typically also pass; the bridge vibrates when the train passes and continues to vibrate even after the train has passed. By analyzing these "residual" vibrations, information on the health status of the bridge can be collected. To imagine the enormous potential of optical fiber for environmental monitoring, just think that, with the interrogation systems developed in Ecstatic, 20 kilometers of fiber are like having a sequence of 2,000 microphones, one every 10 meters, so it is also possible to locate any local anomaly and intervene promptly".

To seize this opportunity, the Ecstatic project will design and develop innovative sensing technologies based on interferometry and polarization, which represent a substantial advancement over the state of the art in fiber optic sensing techniques for vibration and acoustics, in terms of range, sensitivity and localization capabilities. These solutions will offer a wide range of effective options, customizable for different use cases, while ensuring the coexistence of the sensing signal with active data traffic. In the Ecstatic project, the team from the University of Padova will bring its decades-long experience and deep knowledge of the polarization properties of optical fibers. Optical fibers always generate a backscattered light, a kind of weak echo that allows to characterize their local properties. The Padova team will develop a system that, by measuring the polarization of this echo and locating its origin, will be able to transform a submarine link into a sophisticated acoustic and vibration sensor. In conclusion, optical fibers are not only used to transport data along the Internet backbones but can be effective and sustainable tools for security and real-time environmental monitoring.

Luca Palmieri is full professor of Electromagnetic Fields at the Department of Information Engineering of the University of Padova, where he teaches courses on fiber optic communication systems and their use as sensors. He is part of the Photonics and Electromagnetics Group of the Department, internationally renowned for its research carried out in the field of characterization and modeling of innovative optical fibers and their application to environmental, structural and civil monitoring. The Ecstatic Project is implemented by a consortium of 14 European partners: Aston University, Chalmers University of Technology, Enlightra, Modus Research and Innovation, National Observatory Athens, NetworkRail, Nokia, Ote Group of Companies, Sparkle, Universidad de Alcalá, Università degli Studi dell'Aquila, Università degli Studi di Padova, Universitat Jaume I, University of West Attika and has received funding under grant agreement no.