Second-order distortion generated by amplification of intensity-modulated signals with chirping in erbium-doped fiber

A rate equation analysis for second-order distortion generated in an erbium-doped fiber amplifier is reported. It is shown that the relevant mechanism of distortion is the interaction between the frequency chirping of input light and the local gain tilt in the erbium-doped fiber. It is found that the output light distortion is highly affected by the phase difference between the input light distortion and the chirping-induced distortion. This indicates that second-order distortion is not always degraded by erbium-doped fiber amplifiers. >