Solitary pulse propagation in high gain optical fiber amplifiers with normal group velocity dispersion

Pulse propagation in high gain optical fiber amplifiers with normal group velocity dispersion is studied using numerical simulations of a generalized nonlinear Schrodinger equation including a complex Lorentzian gain profile. In particular, when the bandwidth of the input pulse is significantly less than that of the amplifier transition, an initial period of propagation where parabolic pulse characteristics are observed is followed by a solitary wave regime where the pulse temporal and spectral widths are stabilized by the limiting effect of the transition. The intensity and chirp characteristics of the resulting solitary pulse are considered in detail and dimensional analysis yields an empirical expression for the solitary wave peak power in excellent agreement with simulations. (C) 2002 Published by Elsevier Science B.V.