Large refractive index without absorption via quantum interference in a semiconductor quantum well

We investigate the effect of quantum interference on the refractive property in a three-level semiconductor quantum well system. It is found that the refractive properties can be significantly improved via the coupling field, the pumping field and the relative phase. Otherwise, the positive or negative refractive index with vanishing absorption can be also easily obtained in this solid-state system, and the switch between positive refractive index and negative refractive index just by tuning the relative phase.