GAIN TILT OF ERBIUM-DOPED FIBER AMPLIFIERS DUE TO SIGNAL-INDUCED INVERSION LOCKING

The gain tilt responsible for second-order distortion generated by EDF A's in AM TV-systems is shown to be fundamentally different from previ ous belief. The relevant gain-tilt should be measured under locked-inv ersion conditions. It increases with signal saturation and can be sign ificant even at the peak of the saturated gain-curve. Values up to 0.6 dB/nm are measured-60 times higher than previously expected. By prope r EDFA design, the distortion can be reduced to acceptable levels on t he cost of output power.