Mapping the Electromagnetic Near-Field Enhancements of Gold Nanocubes

We imaged and quantitatively characterized electromagnetic hot spots near the surfaces of plasmon resonant gold nanocubes. The strongest fields are localized at the nanocube corners as Compared to those on the sides. The near field enhancement on the surface of the cube was imaged as a function of incident polarization, leading to information on the localization of fields on specific regions on the surface. We found that the field intensity drops dramatically when the nanocube corner is slightly tilted with respect to the incident laser polarization. This dramatic dependence on angle was verified by electrodynamics simulations. These results will enable the use of gold nanocubes in field enhancement applications and refractive index sensing.