Plasmon resonant coupling in metallic nanowires

We investigate the plasmon resonances of interacting silver nanowires with a 50 nm diameter. Both non-touching and intersecting configurations are investigated. While individual cylinders exhibit a single plasmon resonance, we observe uch ore complex spectra of resonances for interacting structures. The number and magnitude of the different resonances depend on the illumination direction and on the distance between the particles. For very small separations, we observe a dramatic field enhancement between the particles, where the electric field amplitude reaches a hundredfold of the illumination. A similar enhancement is observed in the grooves created in slightly intersecting particles. The topology of these different resonances is related to the induced polarization charges. The implication of these results to surface enhanced Raman scattering (SERS) are discussed. (C) 2001 Optical Society of America.