Inelastic wave mixing and multi-photon destructive interference based induced transparency in coherently prepared media

We consider a multi-level medium initially prepared with a coherent superposition of two initial levels that are not directly dipole-coupled. We study the production of multi-wave mixing in the coherent medium, where the process begins on one and terminates on the other of the two prepared levels. We find that a new type of wave mixing field can be efficiently generated in such a system with characteristics of both conventional four-wave mixing and stimulated hyper-Raman emission. We also show that two multi-photon destructive interferences build up simultaneously, leading to simultaneous reduction of the attenuation of the pump and wave-mixing fields. As a consequence a pair of ultra slow, temporally and group-velocity matched pump and wave-mixing fields can be generated. This type of multi-photon induced transparency and its consequences are qualitatively different from the conventional EIT where the destructive interference occurs between two single photon channels. (C) 2004 Elsevier B.V. All rights reserved.