  Electromagnetically-induced transparency (EIT) exploits quantum coherence to
burn subnatural linewidth holes within a spectral line. We investigate the less
explored properties of EIT to effect absorptive nonlinear processes without
restrictions on the relative intensities of pump and probe fields. We show that
a three-level medium under imperfect EIT conditions can generate a form of
bleaching that is qualitatively similar to two-state saturable absorption. This
scheme has the advantages of greater sensitivity to signal intensity and
controllability over its bleaching intensity level post-fabrication. Such
effects could prove useful for noise filtration at very low light levels.
