  We demonstrate that arrays of split ring resonators (SRR) can have negative
refractive index at optical frequencies (~1.4 eV). Our calculations reveal that
the electric fields of radiation interact strongly with even symmetric SRR at
optical frequencies as the size of the SRR becomes of the order of the
wavelength (~lambda /3) for practicably realizable structures. We also
demonstrate by calculations the focussing of a line source by a flat slab of a
(2D) SRR medium. The negative refractive index here is related to the plasmonic
excitations of the SRR and cannot be directly explained by the usual paradigm
of negative dielectric permittivity and negative magnetic permeability in these
limits when homogenization breaks down.
