Erbium-doped fibre amplifiers: the latest revolution in optical communications

Like many technological advances associated with optical fibre communication, erbium-doped fibre amplifiers have moved from the laboratory to the field with extraordinary speed. They are capable of low-noise, low-distortion, high-gain and high-power operation over a broad bandwidth. The paper describes the physical principles behind their operation and shows how their unique characteristics are set to bring about a qualitative change in the way in which optical fibre is used