Abstract

Intensive studies have been made on nonlinear fiber effects, which significantly affect the performance of multi-gigabit cascaded optical amplifier systems [1-3]. Especially in Intensity-Modulated (IM) signals, Self-Phase-Modulation (SPM) induces extra frequency chirping, which results in severe eye degradation through fiber dispersion and set a limit on transmission distance [4]. So far, SPM effect has been evaluated by numerical methods such as the split-step Fourier method [1], albeit they require a large amount of calculation. However, it is shown that the variation of system parameters such as fiber dispersion causes significant effect on transmission distance [5]. Analytical and/or statistical treatment of the SPM is urgently required in designing cascaded amplifier systems, because numerical methods such as Monte-Carlo method would require unrealistic vast amount of calculation. Recently, we proposed an approximate analytical evaluation technique for the SPM effect on the eye penalty after transmission; in which the SPM effect is represented by the increase of α-parameter of the optical transmitter [6].

© 1993 Optical Society of America