Triangle defects in bowtie nanoantennas

Abstract

The surface plasmon resonance (SPR) modes and near field gap enhancement of bowtie nanoantennas with triangle void defects are studied numerically. According to the location of the defects, we classify them into four categories: inner, edge, base and vertex defects. It is concluded that inner and base defects have little impact on both SPR modes and gap enhancement while edge and vertex defects which lead to mode splitting have great impact on the gap enhancement with symmetry breaking. Specifically, the size and location of edge defects have a remarkable effect on the resonant modes, especially for the low-energy resonant mode. When the edge defect gets close to the gap, the gap enhancement increases even above that of bowties with no defects. These properties are instructive to the evaluation of the fabrication of bowtie nanoantennas. And, by careful control of the defect location, we can get useful resonant modes and increase the gap enhancement for applications such as broadband light harvesting, ultra-fast wavelength-sensitive photodetection and fluorescent detection for two or more targets.