  We theoretically demonstrate control of the plasma-like effective response of
a metamaterial composed of aligned metallic nanorods when the electric field of
the incident radiation is parallel to the nanorods. By embedding this
metamaterial in a coherent atomic/molecular medium, for example silver nanorod
arrays submerged in sodium vapor, we can make the metamaterial transmittive in
the forbidden frequency region below its plasma frequency. This phenomenon is
enabled by having Lorentz absorbers or other coherent processes like stimulated
Raman absorption in the background medium which provide a large positive
dielectric permittivity in the vicinity of the resonance, thereby rendering the
effective permittivity positive. In particular, processes such as
electromagnetically induced transparency are shown to provide additional
control to switch and tune the new transmission bands.
