Abstract

The prediction of a collective instability coupling atomic internal and external degrees of freedom [1]a has arisen interest in the possible existence of collective interactions in spectroscopy. Two independent experiments [1]b,c performed in a strongly pumped, off-resonance Sodium vapor have revealed the existence of a gain for a probe beam with characteristics different from those of the well-known mechanisms. A recent calculation [2]a, in which sodium atoms are modeled as as a two-level system without recoil, has been able to account for some of the features of probe gain. The validity of this treatment has been confirmed by spectroscopic measurements [2]b conducted in Potassium vapor.

© 1998 IEEE