Abstract

We report a mechanism that leads to the suppression of line broadening effects. We show that a strong competition between the effects of coherent and incoherent pumps can lead to suppression of spontaneous emission or to narrowing of the spectral profiles. Consider the interaction of a system with a broadband incoherent pump, the effects of which can be accounted for by changing the relaxation times T₁, T₂ in the Bloch equations. For example, for radiative relaxation (rate 2γ) we have where | x | is the Rabi frequency associated with the broadband pump, and Γ is its bandwidth. The spontaneous emission spectrum from such a system in the presence of a coherent drive is the Mollow spectrum with the broadband pump contributing an amount β to the widths of the peaks. We demonstrate that the effects of β can be suppressed if the strength of the coherent pump is such that many Rabi oscillations are possible within the coherence time of the incoherent pump. We show this explicitly by obtaining exact results for spontaneous emission from a model system.

© 1988 Optical Society of America