Microwave-induced coherence effects in refractive index of a V-type three-level atom

A V-type three-level atomic system driven by a coherent field and a microwave field is considered. In this kind of model, the creation of upper level coherence does not require non-orthogonal dipoles. It is found that due to the microwave-induced coherence, refraction-absorption properties can be controlled by the relative phase of applied fields, and high refractive index without absorption can be always achieved just by choosing proper values of the relative phase.