Staircase bowtie nanoantenna and rectangular nanoaperture arrays with huge intensity enhancement as SERS substrates

In this paper, composite nanoantenna arrays are simulative designed for energy harvesting in visible range. The composite nanoantenna on SiO2 substrate consists of staircase bowtie and rectangular nanoaperture. Due to the interaction among rectangular nanoaperture, staircase bowtie and different layers of the staircase bowtie, the designed nanoantenna exhibits an ultrahigh localized intensity enhancement. Results show that the maximum intensity enhancement reaches higher than 9 x 10(4) (E-e(2)/E-0(2)), and the composite nanoantenna can confine electric field distribution uniformly around the bowtie in z direction. When the incident wavelength varies from 660 nm to 760 nm, the intensity enhancement reaches more than 2 x 10(4) (E-e(2)/E-0(2)). The excellent dualresonance enhancement performance of the composite nanoantenna makes it especially suitable for surface enhanced Raman scattering (SERS), the maximum enhancement factor of SERS can reach 2.2 x 10(9).