Characterization of atomic coherence decay for storage of light experiments

We report characterization of EIT resonances in the D1 line of Rb 87 under various experimental conditions. The dependence of the EIT linewidth on the power of the control field investigated. Strictly linear behavior between the ground levels as the main source of decoherence. We therefore formulated a new theory assuming pure dephasing to be the main decoherence mechanism. We also performed experiments where we created additional decoherence mechanisms by means of a counter-propagating repumper field. This field caused the ground-state population exchange, thus reproducing conditions in which the original theory is valid.