Gain-flattened Er/sup 3+/-doped fiber amplifier for a WDM signal in the 1.57-1.60-μm wavelength region

A gain-flattened Er/sup 3+/-doped silica-based fiber amplifier (EDFA) has been constructed for a 1.58-μm band WDM signal. This EDFA exhibits uniform amplification characteristics with a gain excursion of 0.9 dB for a four-channel WDM signal in the 1.57-1.60 μm wavelength region. The average signal gain and the noise figure for the WDM signal are 29.5 dB and less than 6.3 dB, respectively. The use of this EDFA in parallel with a 1.55-μm band EDFA will expand the WDM transmission wavelength region.