Effect of gain dispersion and stimulated Raman scattering on soliton amplification in fiber amplifiers

Amplification of ultrashort solitons in fiber amplifiers is discussed by considering a general model that includes gain saturation, gain dispersion, and intrapulse stimulated Raman scattering. The numerical results show that an interplay between gain dispersion and intrapulse Raman scattering can lead to novel temporal and spectral features. Under high-gain conditions the input pulse is found to split into several subpulses propagating at different speeds. Each subpulse evolves toward a chirped soliton whose width is governed by the gain bandwidth and is ~50 fsec for erbium-doped fiber amplifiers.