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arXiv · 1102.0364

Conversion between electromagnetically induced transparency and absorption in a three-level lambda system

Sapam Ranjita Chanu·Kanhaiya Pandey·Vasant Natarajan
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Abstract

We show that it is possible to change from a {\it subnatural} electromagnetically induced transparency (EIT) feature to a {\it subnatural} electromagnetically induced absorption (EIA) feature in a (degenerate) three-level $Λ$ system. The change is effected by turning on a second control beam counter-propagating with respect to the first beam. We observe this change in the $D_2$ line of Rb in a room-temperature vapor cell. The observations are supported by density-matrix analysis of the complete sublevel structure including the effect of Doppler averaging, but can be understood qualitatively as arising due to the formation of $N$-type systems with the two control beams. Since many of the applications of EIT and EIA rely on the anomalous dispersion near the resonances, this introduces a new ability to control the sign of the dispersion.

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Sapam Ranjita Chanu, Kanhaiya Pandey, Vasant Natarajan. 2012-06-13. Conversion between electromagnetically induced transparency and absorption in a three-level lambda system. https://doi.org/10.1209/0295-5075%2F98%2F44009

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