Local field enhancement of asymmetric metallic nanocylinder pairs

The local field enhancement and surface plasmon resonance of metallic nanoparticles were used to focus and to manipulate light in nanoscale. We investigated the local field enhancement of asymmetric silver nanocylinder pairs by using finite-difference time-domain simulation. The intensity of local field enhancement depends on separation distance, radius ratio, and incident angle of light. Local field enhancement around the smaller nanocylinder was higher and more confined than that of symmetric pairs due to the asymmetric polarization charge distribution on the surface of metallic nanocylinder pairs. Polarization charge distribution of nanocylinder pairs was induced by incident wave and mutual interaction of nanocylinder pairs and the far-field signal showed that the charge distribution was similar to dipole-like charge distribution.