Electromagnetically induced absorption (EIA) in a degenerate closed transition was measured under the action of a probe and a coupling laser of various polarizations giving rise to different possible N-systems or multi-level systems. While the probe shows EIA the coupling is mainly characterized by “absorption within transparency”. However, for certain lasers' intensity ranges, a switch between “absorption within transparency” and “transparency within transparency” in the coupling absorption spectra was measured for the first time.

© 2007 Optical Society of America

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