Fluorescence spectrum of a three-level system driven by a finite-bandwidth squeezed vacuum

Using the coupled-systems approach we show numerically that the fluorescence spectrum from a three-level system driven by a finite-bandwidth squeezed vacuum on one allowed atomic transition and pumped coherently on the other allowed atomic transition may show, in addition to the Autler-Townes doublet, three other peaks. As the bandwidth of the squeezed vacuum increases the three peaks disappear and eventually only the Autler-Townes doublet remains. This is due to a three-wave mixing process.