Applies to optical fibre amplifiers (OFA) using active fibres, containing rare-earth dopants, currently commercially available. The object is to establish uniform requirements for accurate and reliable measurements of the signal-spontaneous noise figure as defined in IEC 61291-1.The test method described is, in general, for multichannel applications. Single-channel applications are a special case of multichannel applications. This second edition cancels and replaces the first edition. It is a technical revision with updated references and cautions on proper use of the procedure.