Abstract

Simulations have shown that the combined effect between the self-phase modulation (SPM) or Kerr nonlinear effect of fiber and accumulated amplified spontaneous emission (ASE) noise of in-line amplifiers in long-haul amplified systems at zero-dispersion degrades the system performance. On the one hand it leads to large broadening of the signal spectrum due to random phase modulation.^1,2 On the other hand it causes the decay of the signal magnitude with exponential of a cubic power of the propagation distance.² It is well-known that using a phase conjugator at mid-way can reduce the effects of the chromatic dispersion and self-phase modulation along a dispersive fiber. In this letter we show that using a phase conjugator can reduce the combined effect of the ASE noise and SPM; on the one hand it reduces the signal spectral broadening, on the other hand it reduces the fading of the signal magnitude.

© 1994 IEEE