Low-noise and high-gain L-band EDFA utilising a novel self-generated signal-seeding technique

A novel technique of generating seed signal to enhance long-wavelength band (L-band) performances of erbium-doped fibre amplifiers is presented. The s eed signal is generated internally using a gain-clamped amplifier based on a ring-laser feedback. This technique has elevated the intensity of a secon dary pump for the L-band amplification compared to the conventional techniq ue of using short-wavelength amplified spontaneous emission (ASE). This str ong seeding signal improves the L-band gain to achieve flat gain where the conventional technique cannot reach this level with the given pump power. T he seeding signal reduces pump-to-ASE losses and noise figure penalties are negligible due to efficient low-noise characteristics in the gain-clamped amplifier. Small signal gains of > 41 dB with noise figures < 4.8 dB are ob tained from this experiment. (C) 2001 Elsevier Science B.V. All rights rese rved.