Local field enhancement tuning of horseshoe-shaped nanoparticles

We proposed a horseshoe-shaped nanostructure formed by etching a gap on a ring structure. By numerical simulations, it was found that the local field of the structure was significantly enhanced compared with that of the traditional ring structure. Furthermore, an additional resonant peak appeared corresponding to the electric field coupling in the gap, and this resonant wavelength was able to be tuned significantly by the particle size, gap size, and gap position. Such properties make the structure promising in biomedical and sensing applications.