Abstract

Recently it has been shown that if two upper levels of a laser system are lifetime broadened and decay by autoionization to the same continuum¹ or by radiation to the same level,² there will be a destructive interference in the absorption profile of low er level atoms, and this interference will be absent from the stimulated emission profile of upper level atoms, thereby allowing the possibility of substantial laser gain without population inversion. This interference, or transparency hole, may exist naturally in the atom system or instead may be created by applying a strong electromagnetic field which couples a relatively metastable level with a rapidly decaying level.³

© 1990 Optical Society of America