OPTICAL SOLITARY WAVES IN THE PRESENCE OF A LORENTZIAN GAIN LINE - LIMITATIONS OF THE GINZBURG-LANDAU MODEL

The domain of validity of the Ginzburg-Landau equation used as a model for describing optical solitary waves in the presence of a distribute d amplification is shown to be restricted to the small-excess-gain reg ion. Our analysis, based instead on a complex Lorentzian gain model, s uggests that, to a good approximation, the main effect of the amplifie r is to select a particular N = 1 soliton of the 'classical' nonlinear Schrodinger equation. Analytical approximations accurately describe t his process. (C) 1998 Elsevier Science B.V.