ABSTRACT
The use of optical amplifiers affects the evolution of solitons considerably. The reason is that, although amplifiers are necessary to restore the soliton energy, they add noise originating from amplified spontaneous emission (ASE). The effect of ASE is to change the soliton parameters randomly. Variances of such fluctuations can be calculated by treating ASE as a perturbation. Besides deterministic-type perturbations, one also needs to take into account, for practical considerations, stochastic-type perturbations. The amplifiers that are placed along soliton transmission lines to restore soliton energy introduce noise that originates from ASE. In the case of lumped amplification, solitons are perturbed by ASE in a discrete fashion at the location of the amplifiers.
