Abstract

It is well-known that coupling of a strong optical radiation with a three-level systems is accompanied by the interference of the quantum pathways. This may cause the elctromagnetically induced transparency (EIT),¹ and at the same time improvements in nonlinear frequency-mixing susceptibility and phase-matching.² In more general cases, quantum interference causes a difference in interaction of probe radiation with absorbing and emitting atoms and may lead to the amplification of probe radiation without population inversion.³ In nonlinear optics EIT makes it possible to increase the number density of the nonlinear atoms.

© 1994 IEEE