Gap enhancement and transmittance spectra of a periodic bowtie nanoantenna array buried in a silica substrate

The gap enhancement and transmittance spectra properties of a periodic outline bowtie nanoantenna array (POBNA) which is embedded in a substrate with different depths are numerically investigated by using the finite element method. The surface plasmon resonance (SPR) modes obtained from the embedding cases are quite different from that of the free standing case. Near-field interactions across the bowtie-gaps and POBNA hollows at the localized SPR wavelengths resulted in an increase of magnitude in local field intensity and a redshift of transmittance resonance dip wavelength. The POBNA embedded in a silica substrate can be used as critical elements for nanoscale optical devices.