Erbium-doped fibre pre-amplifier with an integral band-pass filter

The authors have shown that significant optical gain improvements can be achieved by inserting a narrow band-pass filter within the erbium-doped fibre amplifiers length to suppress the built-up of both forward and backward ASE powers, accompanied by a noise figure reduction of 0.6-0.8 dB. The optimum filter position is found to be around 48% and 42% from the input end of the total amplifier length for 1.48 mu m and 0.98 mu m pump wavelengths respectively.<
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