In-plane coupling and field enhancement in infrared metamaterial surfaces

In-plane coupling between the second plasmonic mode of split ring resonators and delocalized plasmons of nanowires is experimentally demonstrated from far-field measurements in metasurfaces with critical separation distances between nanostructures. Near-field calculations show that coupling drastically depends on both meta-atom shapes and separation distances. The associated field enhancement reveals these metasurfaces as good candidates for applications to sensing and surface enhanced spectroscopy.