Time dependent fluorescence spectrum of a three-level Λ system under electromagnetically induced transparency and coherent population trapping

We investigate theoretically the time dependent fluorescence spectra (TDFS) of a three-level system in electromagnetically induced transparency (EIT) and coherent population trapping (CPT) configurations. Time dependent fluorescence intensities of Rayleigh and Stokes transitions are studied as a function of the ground state coherence relaxation rate and initial state preparation, and their correlation with the temporal evolution of dark and bright states is established. Linewidths of fluorescence and absorption are compared in different regimes of relaxation rates. The results are used to discuss the characteristic features of EIT and CPT in the domain of fluorescence spectroscopy.