This International Standard applies to all commercially available optical amplifiers (OA) and optically amplified subsystems. It applies to OA using optically pumped fibres (OFA based on either rare-earth doped fibres or on the Raman effect), semiconductors (SOA), and waveguides (POWA). NOTE The applicability of the test methods described in the present standard to distributed Raman amplifiers is for further study. The object of this standard is to establish uniform requirements for accurate and reliable measurements, by means of the optical power meter test method, of the following OA parameters, as defined in Clause 3 of IEC 61291-1: nominal output signal power; gain; reverse gain; maximum gain; polarization-dependent gain; large-signal output stability; saturation output power; maximum input signal power; maximum output signal power; input power range; output power range; maximum total output power. In addition this test method provides a means for measuring the following parameters: maximum gain wavelength; gain wavelength band. NOTE All numerical values followed by (‡) are suggested values for which the measurement is assured. Other values may be acceptable but should be verified. The object of this standard is specifically directed to single-channel amplifiers. For multichannel amplifiers, one should refer to the IEC 61290-10 series1.