Supplementary Material

A validation of the COMSOL based Scattering efficiency calculations is shown using the boundary element method (BEM) based MNPBEM (metallic nano-particle BEM) codes \cite{hohenester2012mnpbem} as well as through the analytical expressions from the electromagnetic scattering theory \cite{Bohren1998}. It also provides a discussion on the reflectance spectra of the TiO$_2$ coupled-dipolar antenna structure on a Ag reflector layer and the optimization curves for the TiO$_2$ cylinder's length, $L$ under plane wave excitation.