This part of 61290 applies to commercially available optical fibre amplifiers (OFAs) using active fibres containing rare-earth dopants as described in the following. The object of this international standard is to establish uniform requirements for accurate and reliable measurements of the multichannel gain and noise parameters as defined in IEC 61291-4. The test methods described in this standard use small-signal probes to obtain the multichannel gain and noise parameters while one or more lasers set the saturation condition for the OFA. These methods are classified as indirect in that there is not a laser source at each wavelength of the multichannel plan. Multichannel parameters are estimated from the probe data. IEC draft standards 61290-10-1 and 61290-10-2 are test methods for measuring noise parameters using pulse techniques. These methods are direct in that the multichannel source is required to have a laser at each wavelength for which multichannel parameters are to be measured. Probe techniques provide clear advantages for measuring multichannel gain characteristics in that a simple source confirguration can provide parameters for a wide range of multichannel plans. Either a small-signal laser or a broadband noise source serves as the probe signal, and single or multiple lasers are used to set the OFA saturation condition. Pulse modulation of the saturating sources may optionally be used to measure ASE at or near the saturating laser wavelengths without the contaminating effect of source spontaneous emission.