  The spectral response of a plasmonic nanostructure may heavily depend on the
refractive index of its surroundings. The key idea of this paper is to control
this response by coherent optical means, i.e. with an optically controlled
electromagnetically-induced-transparency medium. In such environment, an
external laser provides a knob to shift the position of plasmonic resonances
without the need to change the geometry of the nanostructure. Additionally, the
setup can be exploited to excite narrow-band surface plasmon polaritons.
