Localized surface plasmons in disk supershape shell nanoparticles

Here, we reported the excitation of multiple localized surface plasmons in disk supershape shell nanoparticles using the finite difference time domain method. All plasmon bands of disk supershape shell nanoparticles were extracted from extinction spectra. The characteristics of the plasmon bands were investigated as functions of the structural parameters of the shell nanoparticles and the refractive indices of the environment and substrate. The obtained results showed in general, two types of plasmon bands appear, one at longer wavelengths and the other at shorter wavelengths, which are, respectively, dependent on the excitation of dipoles and higher-order multipoles. The patterns of the electric field and charge distribution prove these points. The Purcell factor spectra revealed that the resonant modes corresponding to plasmonic bands occur in the emission spectra, although new modes appear between them due to the asymmetry of the nanoparticle geometry. This study could potentially have applications in sensors, thermal photonics, and energy harvesting.