Study on noise characteristic of gain-clamped erbium-doped fiber-ring lasing amplifier

A simplified method to estimate the noise figure of the optically gain-clamped erbium-doped fiber amplifiers (EDFA´s) is proposed. The simulation results indicate that the population inversion level at the signal input end dominates the noise performance of the entire amplifier. For a gain-clamped EDFA with ring-lasing configuration, the effects on the noise figure of the amplifier by the distributions of the pumping and lasing powers as well as the lasing wavelength are analyzed theoretically. The suggested noise-optimum configuration is co-pumping and co-traveling lasing oscillation at 1531 nm. Near quantum limit internal noise figure of 3.6 dB is achieved in the experiments under the best arrangement. The experiment results show perfect accordance with the theoretical analysis.