broadband fibre

Fibre-optic sensors could transmit data up to 100 times faster

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Researchers from the École polytechnique fédérale de Lausanne (EPFL) have developed an encoding and decoding system which allows fibre-optic sensors to send data up to 100 times faster, and over a wider area.

Distributed fibre-optic sensors are commonly used in hazard detection systems to identify potential accidents before they happen, such as spotting cracks in pipelines, detecting potential landslides on mountain slopes, or identifying deformations in structures. These sensors can take temperature readings everywhere a fibre is placed, generating a continuous heat diagram of a site (even if the site stretches over tens of kilometres).

“Unlike conventional sensors that take measurements at a given point, like thermometers, fibre-optic sensors record data all along a fibre,” said Professor Luc Thévenaz, head of the Group for Fibre Optics at EPFL. “But the technology has barely improved over the past few years.”

Two engineers at the group, working with the Beijing University of Posts and Telecommunications, developed a new system for encoding and decoding the data sent along the fibres.

They describe the sensing process as like listening to echoes; an echo of many words blended together is unintelligible without a key to decipher the sounds. The sensors function in a similar manner, except they use light pulses rather than sounds; the signals bounce up the fibre and a device decode them, turning them into usable data.

In order to make the sensors more efficient, the researchers grouped the light pulses into sequences such that the signals bounce back with greater intensity. In order to resolve the 'echo' problem (making the signals intelligible), they developed a method which uses genetic optimisation algorithms to encode the data sent along fibres.

“Other systems are either limited in scope or expensive,” said 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.”

Using their method, sensors can outperform state-of-the-art systems, receiving higher-energy signals and decoding them faster. This resulted in measurements taken more rapidly – up to 100x more rapidly – and over a considerably larger area.

The study describing the development of the system has been published in Nature Communications.

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