High refractive index without absorption via spontaneously generated coherence and incoherent pumping

We studied a closed three-level V-type system with two near-degenerate excited levels in the presence of an incoherent pumping field. Quantum interferences of the two-decay channels lead to the achievement of the high index of refraction without absorption via spontaneously generated coherence. We use the exact analytical formula of the refractive index derived by us in a recent paper. We found that the high refractive index varies very much with the angle between the two dipole moments and evidently with the detuning of the coupling field.