Heliograph in use via Wikimedia Commons.

Professor Polina Bayvel (UCL Electronic & Electrical Engineering) opened her Lunch Hour Lecture with the worrying fact that our internet capacity is finite and we are fast approaching that limit. What can we do to find new capacity so that our optical fibre can manage the growth of the coming decades?

Professor Bayvel explained that optical communications have been a part of human communications for millennia. Fire and smoke signals, heliographs and Aldis lamps (which both use flashes of light to signal) are all forms of communication called “free space communications”. These were important for our predecessors’ long distance communications, but with the major flaw that they didn’t work on cloudy or otherwise poor visibility days.

Modern communications are almost entirely built around optical fibre networks. These work by bouncing beams of light along glass cables. The light is received and decoded into whatever information was requested. They allow huge amounts of data to travel long distances, and with the help of repeaters which receive the signal and rebroadcast it, can travel around the whole world.

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