Optical scattering and electric field enhancement from core-shell plasmonic nanostructures

Three-dimensional finite-difference time-domain simulations are used to study the near-and far-field properties of plasmonic core-shell (CS) nanostructures of reduced symmetry. Special attention is given to silica core and gold shell nanoparticles by changing their geometry. For the simulated range of wavelengths (300-2100 nm) our calculations of the scattering and absorption efficiencies imply strong polarization sensitivity and are highly dependent on the size and geometry of the CS nanostructures. Strong enhancements of the exciting electric field associated with the excitations of nanoparticle plasmons are observed. The wavelength dependence of the scattering spectra and concentration of electromagnetic field in subwavelength volumes have a potential for biosensing and bioimaging. (C) 2011 American Institute of Physics. [doi:10.1063/1.3660774]