Gain enhanced L-band Er/sup 3+/-doped fiber amplifier utilizing unwanted backward ASE

A novel method of enhancing gain in the long wavelength band erbium-doped fiber amplifier is described using the unwanted amplified spontaneous emission (ASE) self-pumping technique. A dual-stage amplifier is deployed, where the unwanted backward ASE from the first stage is fully utilized to pump the second stage amplifier. Gain improvement is observed that enables support for higher channel capacities in wavelength-division-multiplexed systems with negligible noise figure penalties. Flat-gain values in excess of 24 dB and noise figures <5 dB are obtained from the proposed amplifier with a higher channel counts compared to the conventional amplifier.