  Fiber guided optical signal propagating in a Erbium doped nonlinear resonant
medium is known to produce cleaner solitonic pulse, described by the self
induced transparency (SIT) coupled to nonlinear Schroedinger equation. We
discover two new possibilities hidden in its integrable structure, for
amplification and control of the optical pulse. Using the variable soliton
width permitted by the integrability of this model, the broadening pulse can be
regulated by adjusting the initial population inversion of the opant atoms. The
effect can be enhanced by another innovative application of its constrained
integrable hierarchy, proposing a system of multiple SIT media. These
theoretical predictions are workable analytically in details, correcting the
limitation of a well known result.
