Plasmonic Interaction between Overlapping Nanowires

The plasmonic interaction between overlapping nanowires with and without structure singularities is studied analytically and numerically. A conformal transformation approach is adopted to predict analytically the optical response of overlapping nanowires in the quasi-static limit. Surface plasmon excitations are shown to exhibit a lower bound cutoff frequency, which blue-shifts when the overlap distance increases. Between this cutoff and the surface plasmon frequencies, overlapping nanowires are capable of a strong and broad-band harvesting of light. This band gap feature is shown to be robust to radiative losses and to the bluntness of the structure singularities. Hence, the light harvesting performance of overlapping nanowires would not be damaged by nanofabrication imperfections. These remarkable features might be beneficial to the realization of plasmonic band gap filters.