SPECTRAL STRUCTURES INDUCED BY ELECTRON SHELVING

We investigate the spectrum of resonance fluorescence of laser-driven three-level systems in the V or Lambda configuration where one transit ion is metastable. If the laser driving the weak transition has a suff iciently small Rabi frequency we find an extremely narrow structure in the resonance fluorescence spectrum of the strong transition. Analyti cal expressions approximating the spectrum are given and the propertie s of the spectrum are discussed. With the help of a simplified model o f resonance fluorescence emitted on the strong transition we are able to show that the origin of the narrow peak can be traced back to elect ron shelving, i.e., to the existence of light and dark periods in the resonance fluorescence emitted on the strong transition.