The fiber amplifier WDM enables the combination of pump and signal in C-band 980nm pumped Erbium Doped fiber Amplifiers (EDFA). The uniquely low insertion loss of this component, across the whole C-band, enables manufacturers to achieve the lowest noise figure in their amplifiers. Similarly low loss in the 980nm window maximizes the pump power reaching the Erbium fiber. Applications include EDFAs for dense WDM systems, pre and post amplifiers and optical noise sources. 980/1550nm WDMs are manufactured using optical fiber with numerical aperture intermediate between that of signal and gain fiber to enable mode-field matching and bend-insensitive single mode operation at both wavelengths.