We report on three-photon electromagnetically induced absorption (TPEIA) due to three-photon coherence in ladder-type atomic systems for the
5S1/2-
5P3/2-
5D5/2 transition in Rb atoms. When a counterpropagating coupling field was added to the typical ladder-type electromagnetically induced transparency (EIT) experiment, both EIT and two-photon absorption (TPA) switched to TPEIA. Considering three-photon coherence in a Doppler-broadened three-level ladder-type atomic system, the spectrum of the switch from EIT and TPA to TPEIA was numerically calculated and could be understood by decomposing the calculated spectrum into two-photon coherence and three-photon coherence components.
We discuss the features of the electromagnetically induced transparency (EIT) in a ladder-type three-level atom-cavity system. It is shown that the presence of the strong pump field leads to the appearance of two additional windows. Meanwhile, the dispersion profiles are also modified. A steep dispersion appears in each reflection peak. The position of these windows depends on the values of the detuning Delta(2) of the control field. Moreover, it is viable to create the gain profiles when the cavity detuning Delta(c) not equal 0.