Electromagnetically induced absorption in quasi-degenerate two-level Doppler broadened atomic system.

We report, in this paper, a narrow dip of electromagnetically induced absorption inside the optical pumping window by the interaction of two coherent laser fields with a quasi-degenerate two-level open atomic system in inhomogeneously broadened Rb vapour. The effect arises from optical pumping and laser-induced atomic multilevel Zeeman sublevels in the same ground state. The numerical simulation for a N -type four-level system shows good agreement with experimental observation. [ABSTRACT FROM AUTHOR]