Phase dependent coherent control of group delay in a doped metamaterial slab

A scheme is proposed for the coherent control of the group delay for a light beam traveling through a double-negative metamaterial (DNM) slab. By doping three-level atoms into the DNM slab, phase control over the transmission and reflection behaviors of the active layer is achieved. This way, tunable and simultaneous subluminal and superluminal transmission and reflection are achievable. We discuss the effect of the relative phase of the applied fields and the rate of incoherent pumping on the group delay of a probe pulse propagating through the DNM slab. It is shown that group delays of the transmitted and reflected beams are completely phase dependent. We also find that transmission of a probe field propagating through the DNM slab is actively controllable in a wide range by controlling the relative phase of the incident fields with no need to alter physical parameters of the metamaterial.