How does a fibre-optic strand thinner than a spaghetti noodle carry a signal across 13,000 kilometres of ocean without a single electrical…

The undersea cables that carry nearly all of the world's internet traffic rely on a trick worked out in a Southampton laboratory in the late 1980s: glass fibres doped with a rare-earth element that amplify light without ever converting it back to electricity.

By How It Works · Aug 21, 2026