Abstract
We experimentally demonstrate the polarization-dependent plasmonic resonances in split-ring resonators (SRRs) by performing normal incidence reflection measurements, leading arbitrary electric excitations to two distinct groups of magnetic and electric resonances. The origin of these resonances is elucidated by both quantitative spectroscopic measurements and the distribution of the simulated surface current density, indicating that the plasmonic resonances of the SRRs stem straightforwardly from the superposition of two orthogonal electric excitations. Such plasmonic resonances in SRRs enable controllable effective electric permittivity by tuning various polarization angles of electric excitations, offering the flexibility of manipulating electric permittivity for diverse practical applications. © 2009 IOP Publishing Ltd.