Gain characteristics of erbium-doped fibre amplifiers with high erbium concentration

The gain characteristics of erbium-doped fibre amplifiers with erbium concentrations as high as 8900ppm have been investigated with 0.98 and 1.48μm pumping schemes. In spite of the gain decrease due to the high erbium concentration, a gain as high as 24dB was obtained with a 50cm long fibre at a pump power of 60mW. An output power of + 8dBm was also obtained for a pump power of 60mW with both 0.98 and 1.48μm pumping. The 0.98μ pumping scheme is suitable for high concentration EDFAs.