Sending large amounts of information down an optical fibre is done by encoding many separate streams of data as pulses of light of different colours, so that they can travel along the fibre without interfering with each other.

ECONOMIST: Optical fibres could carry more information in the future

Optical correlators, meanwhile, work by encoding images on to a beam of light and, using a special lens, transforming them into their Fourier components building-blocks that encode the thickness and direction of lines in the image, but not their position.

ECONOMIST: Optical recognition