Gain from cross talk among optical transitions

Abstract

We analyze the probe absorption spectra of a strongly driven $\ensuremath{\Lambda}$ system with arbitrary spacing between the two lower levels. Under the condition that the spacing between the two lower levels is of the order of a strong-pump-field Rabi frequency, important interference effects are observed due to same-field coupling with both the transitions. We report the possibility of a significant gain from the cross talk among optical transitions, and a strong dependence of gain and absorption on the relative polarizations of the pump and probe beams. We present an analysis based on dressed states to explain our numerical results.