Tech UPTechnologyFiber optic cables could be used to spy on...

Fiber optic cables could be used to spy on people a kilometer away

Fiber optic cables, such as those used in the Internet network infrastructure, could be used for eavesdropping or eavesdropping, without us being aware of it. A device that can pick up small changes in signals sent down wires can detect words spoken more than a kilometer away, scientists have discovered.

Optical fibers use beams of light to carry data around the world, underground and in the oceans. However, a team of scientists at Tsinghua University in Beijing, China, has developed a system that picks up sound at one end of a fiber-optic cable and transmits audio at the other end.

How is it possible?

Fiber optic cables use pulses of light to transmit data but are sensitive to changes in ambient pressure, which could be caused by acoustic waves, such as the sound of someone speaking.

“Fiber optic networks are widely deployed throughout the world, which not only facilitates the transmission of data, but also offers the opportunity to obtain additional information,” they say in their article. These applications of fiber optic networks, including earthquake detection, urban traffic flow monitoring, and exploration of underground geological structures, have a positive impact on production and people’s lives. However, it also brings some potential security issues, which should be carefully considered,” the authors explain.

The sound signals could be modulated on the light wave transmitted by the fiber, without installing any additional equipment in the resident’s home. This would allow other people to eavesdrop and retrieve them at remote locations along the fiber link. This is because fiber optic networks are quite sensitive to vibration. (Which would lead to capture any conversation).

They say the espionage method requires “complicated equipment and strict conditions”, but add that ” secret theft behavior will always be performed regardless of cost”.



Referencia: Indoor optical fiber eavesdropping approach and its avoidance. Haiqing Hao (1), Zhongwang Pang (1 and 2), Guan Wang (1 and 2), Bo Wang (1 and 2) ((1) State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing, China, (2) Key Laboratory of Photonic Control Technology (Tsinghua University), Ministry of Education, Beijing, China) Optics Express 2022 DOI:


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