Applies to optical fibre amplifiers (OFAs) using active fibres, containing rare-earth dopants, currently commercially available. The uniform requirements for accurate and reliable measurements of the signal-spontaneous noise figure as defined in 3.1.18 of IEC 61291-1 are established. The test method independently detects amplified signal power and amplified spontaneous emission (ASE) power by launching optical pulses into the OFA under test and synchronously detecting "on" and "off" levels of the output pulses by using an optical sampling switch and an optical spectrum analyzer (OSA).