Double electromagnetically induced two-photon transparency in a five-level atomic system

When the intermediate level in a ladder-type atom is coupled with a higher-excited and a ground levels by two control fields, there appear double electromagnetically induced transparency windows in the two-photon absorption spectra. The effects of the Rabi frequencies and the detunings for the control fields on the two-photon absorption spectra are also investigated. Finally, the explanations of these phenomena and the conditions of the absorption minimums are given by using the dressed states.