SPONTANEOUS EMISSION SPECTRA AND SIMULATING MULTIPLE SPONTANEOUSLY-GENERATED COHERENCE IN AN N-TYPE MEDIUM

Abstract

We investigate the spontaneous emission spectra of a coherently driven four-level cold atomic system. It is shown that a few interesting phenomena such as spectral-line narrowing, spectral-line enhancement, spectral-line suppression, and spontaneous emission quenching can be realized in our system. The spectral-line enhancement and suppression can be conveniently manipulated by appropriately modulating the frequency detuning of the probe driving field. In the dressed-state picture of the probe and coupling fields, we find that this coherently-driven atomic system has three close-lying levels so that multiple spontaneously-generated coherence (SGC) arises. Our considered atomic model can be found in real atoms, such as rubidium or sodium, so a corresponding experiment can be done to observe the expected phenomena related to SGC effect, since no rigorous conditions are required.