Mutual signal gain saturation in Er/sup 3+/-doped fibre amplifier around 1.54 mu m wavelength

Signal gain saturation characteristics of a 1.48 mu m wavelength laser diode pumped Er/sup 3+/-doped fibre amplifier are experimentally investigated for two signal channels amplified around the gain peak wavelengths of 1.535 mu m and 1.551 mu m. The degree of gain saturation is uniquely determined by the total output power when the signal wavelengths are closely positioned. This feature is not suited to two-channel amplification for widely spaced wavelengths.