This document deals with high-power optical amplifiers. It provides general information relating to high-power optical amplifiers with an output power greater than 500 mW for the fibre communication field. It covers the following aspects: ?C general information; ?C example of the optical amplifier's configuration realizing high optical output power; ?C test method for optical output power and gain; ?C considerations on high-power optical amplifiers. Potential applications of high-power optical amplifiers are briefly reviewed in Annex A. Informative IEC documents related to high optical power are listed in Annex B.