  This work models the propagation of an optical pulse in a 4-level atomic
system in the electromagnetic induced transparency regime. By demonstrating
that linear and nonlinear optical properties can be externally controlled and
tailored by a continuous-wave control laser beam and an assisting incoherent
pump field, it is shown how these media can provide an excellent framework to
experimentally explore pulse dynamics in the presence of non-conservative
terms, either gain or loss. Furthermore, we explore the existence of stable
dissipative soliton solutions, testing the analytical results with
computational simulations of both the effective (1+1)-dimensional model and the
full Maxwell-Bloch system of equations.
