Fiber-Optic Sensors Transmit Data up to 100 Times Faster

Simon Zaslawski, Zhisheng Yan and Luc Thévenaz developed new fiber optic sensors – used in critical applications like detecting fires in tunnels. (Source: A. Herzog, EPFL)

Engineers from the Swiss Federal Institute of Techno­logy (EPFL) have developed an advanced encoding and decoding system that allows fiber optic sensors to send data up to 100 times faster and over a wider area. “Unlike conven­tional sensors that take measure­ments at a given point, like therm­ometers, fiber optic sensors record data all along a fiber,” says Luc Thévenaz, head of the group for fiber optics (GFO). “But the techno­logy has barely improved over the past few years.”

Fiber optic sensors are commonly used in hazard detection systems, such as to spot cracks in pipelines, identify defor­mations in civil engineering structures and detect potential landslides on mountain slopes. The sensors can take tempera­ture readings everywhere a fiber is placed, thereby gene­rating a continuous heat diagram of a given site – even if the site stretches for dozens of kilo­meters. That provides crucial insight into possible accidents before they happen. Working in asso­ciation with the Beijing University of Posts and Telecommu­nications, two GFO engineers – postdoc Zhisheng Yang and PhD student Simon Zaslawski – developed a new system for encoding and decoding data sent along the fibers. With their method, sensors can receive higher-energy signals and decode them faster, resulting in measure­ments taken more rapidly and over a larger area.

The engineers describe their system as working like an echo. If you shout a single word, you hear that word back. But if you sing out a song, what you hear back is a blend of sounds that are hard to distin­guish. You would need a key to decipher the sounds and make them intelli­gible. Fiber optic sensors function in a similar manner, except that an instrument sends out light pulses – rather than sounds – along a fiber. Signals bounce back up the fiber and a device decodes them, turning the signals into usable data.

To make the sensors more efficient, Yang and Zaslawski grouped the light pulses into sequences so that the signals bounce back with greater intensity. However, that didn’t solve the echo problem – that is, finding a key to make the signals readable. So they developed a method for encoding the data sent along a fiber; their method employs special genetic optimi­zation algorithms to cope with imper­fections. “Other systems are either limited in scope or expensive,” says Thévenaz. “But with ours, you just have to add a software program to your existing equipment. No need to adapt your sensors or use complex devices.” (Source: EPFL)

Reference: X. Sun et al.: Genetic-optimised aperiodic code for distributed optical fibre sensors, Nat. Commun. 11, 5774 (2020); DOI: 10.1038/s41467-020-19201-1

Link: Group for Fiber Optics (GFO), Institute of Electrical Engineering, Swiss Federal Institute of Technology Lausanne EPFL, Lausanne, Switzerland

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