CREATION OF SOLITONS FROM A LONG SIT PULSE

The theory of soliton formation in the vicinity of the sharp front of a light pulse propagating in a two-level resonant medium is developed. The process is described in terms of the modulational Whitham theory applied to the periodic solution of the self-induced transparency (SIT ) equations. The self-similar solution of the Whitham equations is obt ained corresponding to the decay of a step-like pulse. It is shown tha t this solution generalizes the cases of the NLS equation and the AB s ystem studied earlier.