Decay of an optical pulse in a nonlinear fiber at the zero dispersion point

The geometric optics (WKB) approximation is used for the description of the evolution of an initially rectangular pulse in the nonlinear fiber at arbi trary distances of propagation. The exact solution of the equations is foun d for the case of a simplified model used earlier in the theory of the cont rol of the pulse form by means of the initial chirp. The asymptotic form of the pulse shape in the long distance limit is found explicitly. (C) 2000 E lsevier Science B.V. All rights reserved.