Near-field optical experiments on low-symmetry split-ring-resonator arrays.

Effective symmetric and antisymmetric eigenmodes of coupled plasmonic resonances play a crucial role in many photonic metamaterials. Recently, we discussed a particular arrangement of metallic split-ring resonators that is planar, hence enabling direct experimental access to the different eigenmodes via near-field optical microscopy. In this Letter, corresponding optical experiments are presented and compared with simple theoretical modeling, providing a direct confirmation of our previous, more indirect conclusions.