Plasmonic Properties Of Dielectric-Core Plasmonic-Shell Nanocylinders In Pascal Triangle

Abstract

We report on the plasmonic properties of silver-coated dielectric nanocylinders arranged according to an unconventional geometrical representation called Pascal's triangle. We performed numerical simulations to calculate the extinction spectrum and identify the collective optical modes in the geometry. For resonant excitation at 410 nm, we found pronounced field localization (50 nm) at the center of the Pascal triangle. Further, we studied the near-field intensity as a function of experimentally-relevant variables such as excitation wavelength, angle of incidence and dielectric constant of the core material. Our analysis revealed pronounced difference between near-field intensities for resonant and non-resonant excitation wavelength at various angle of incident radiation; and an increment in near-field intensity at excitation wavelengths greater than 600 nm, with increase in dielectric constant of core material. Our study has relevance in development of substrates with tunable electromagnetic hot-spots for on-chip plasmonics.