Transmission and saturation performance of dispersion-shifted distributed erbium fibre

The gain spectra for a bidirectionally pumped 30 km length of lightly doped dispersion shifted erbium fibre and the amplification performance in saturation of a 54 km length of similar fibre are presented. The longer length comprised six spliced fibres with an average erbium concentration in the core of approximately 60 p.p.b. and could be rendered lossless with 2*30 mW of pump power for low power signals. With 2*55 mW of pump power a peak fibre gain of 17 dB at 1536 nm was realised; as the input signal power was increased the gain was suppressed but the fibre remained transparent for signal powers up to -2 dBm.