This International Standard applies to all commercially available optical amplifiers (OAs), including OAs using optically pumped fibres (OFAs based on either rare-earth doped fibres or on the Raman effect), semiconductor optical amplifiers (SOAs) and planar waveguide optical amplifiers (PWOAs). The object of this standard is to provide the general background for OA noise figure parameters measurements and to indicate those IEC standard test methods for accurate and reliable measurements of the following OA parameters, as defined in IEC 61291-1: a) noise figure (NF); b) noise factor (F); c) multiple path interference (MPI) figure of merit; d) signal-spontaneous noise figure; e) (equivalent) spontaneous-spontaneous optical bandwidth (Bsp-sp); f) forward amplified spontaneous emission (ASE) power level; g) reverse ASE power level; h) ASE bandwidth. This standard addresses measurement of OAs that are to be used for amplifying single channels, that is signals from a single transmitter. Testing of OAs for multichannel use involves additional considerations, such as: the number, wavelengths and relative power of the signals, the ability to measure signals simultaneously and to measure the ASE between channels. NOTE Methods for measurement of OAs for multichannel use are included in the IEC 61290-10 series.