Numerical simulations of plasmonic properties of spherical gold nanodisks using T-matrix method: impact of geometry parameters on the sensitivity to the dielectric environment and the field enhancement

Simulations using the transition matrix approach are implemented for spherical gold nanodisks (AuNDs) to obtain insights into their plasmonic properties. We systematically follow the correlation between the optical response of these nanostructures with their geometry parameters and the refractive index of the surrounding medium. Plasmon wavelengths linearly redshift with the diameter-to-height aspect ratio, which is consistent with measured data available in the literature, thereby ensuring calculation accuracy. The relative plasmon resonance shift to the relative increment of the medium refractive index is geometry-dependent and exhibits a linear correlation in which the estimated slope represents the plasmon resonance sensitivity. We confirm the strong dependence of the field enhancement factor on the geometry parameters of nanodisks. The relative contributions of scattering and absorption in the extinction spectra are determined. Simulations show that circular AuNDs have well-controlled optical characteristics that will provide great opportunities to achieve various plasmon-derived applications.