ABSTRACT

Theoretical and experimental work of the past few years has demonstrated that the optical response of multi-state atomic systems can be controlled efficiently using quantum coherence and interference effects. These effects include: lasers operating without population inversion, novel techniques for resonantly enhanced nonlinear optics, enhancement and manipulation of the refractive index, and modification of spontaneous emission. In the present paper, we discuss manifestations of these effects of quantum interference in one of the simplest multilevel atomic system, in which two upper levels are coupled a static field. In this way we probe the extent to which optical of such systems can be "engineered" using atomic coherence. The present treatment provides useful insights into the physics of this phenomenon.