Elimination of the transient absorption in a microwave-driven Λ-type atomic system

We investigate the absorption properties of the transient process in a three-level Λ-type atomic system driven by a coherent field and a microwave field. It is shown that, by modulating the relative phase of the applied fields, the absorption properties of the transient process can be dramatically changed. The transient absorption can be eliminated just by tuning the relative phase of the applied fields into proper regions