The localized near-field enhancement of metallic periodic bowtie structure: An oscillating dipoles picture

The metallic periodic bowtie structure is systematically investigated using a three-dimensional finite difference time domain (FDTD) method. The oscillating dipoles picture is proposed to explain the novel enhancement of localized near-field. It is indicated that the shift and the intensity change of notable resonant dips in the transmission spectrum result from the variation of localized surface plasmon resonance (LSPR) conditions due to the different geometrical sizes of the structure and the array periodicity. The results are helpful for guiding the bowtie structures to the application of the near-field imaging and sensing in the subwavelength optics.