Abstract

Recently there has been considerable interest in lasing without population inversion. This feature is based on quantum interference effects in multilevel atoms which create different absorptive and emissive properties of the atom. With reduced absorption it is possible to achieve gain without requiring an inversion in any atomic basis (dressed or bare). Such a system has been proposed by Imamoğlu et al^[1] in a three level atomic system in a Λ configuration. A coherent field is applied to one of the transitions which dresses the atomic levels. Agarwal^[2] has shown that the origin of the amplification in this system is the coherence between the two dressed states. This is an example of light amplification by coherence (LAC). We shall present a full quantum statistical analysis of this system and determine the photon statistics of the light both inside and emerging from the cavity. Since lasers without inversion operate with low absorption and hence reduced spontaneous emission a sub shot noise output is possible.

© 1992 IQEC