Four-wave mixing in dressed cold cesium atoms

Quasi-degenerate four-wave mixing optical phase conjugation was investigated in cold cesium atoms confined in a magneto-optical trap. Broad and narrow resonances were observed in the corresponding spectrum. The broad resonances reveal directly the dressed levels structure of the composite system formed by atoms and trapping laser field. However, the observed narrow resonances can only be qualitatively understood in terms of Raman processes involving nearly degenerate ground-state levels, indicating the important role played by the level degeneracy. (C) 2000 Published by Elsevier Science B.V.