In-line amplifier transmission distance determined by self-phase modulation and group-velocity dispersion

The propagation of an intensity-modulated signal in an optical fiber is numerically analyzed, taking self-phase modulation, group-velocity dispersion, and 2nd-order group-velocity dispersion into account. Transmission distances yielding a prescribed eye-opening penalty are shown to relate to three characteristic lengths: the dispersion length, the 2nd-order dispersion length, and the nonlinear length. These relations, with a slight modification for the signal power, are also found to be valid for in-line amplifier systems, in which each optical amplifier, though adding undesired amplified spontaneous emission, compensates the signal attenuation occurring in the preceding fiber. The resulting relations give us informative guidelines for designing such systems