Optical properties of anisotropic 3D nanoparticles arrays

Abstract

-The optical properties of 3D periodic arrays of spheroidal Au nanoparticles are calculated using a Bruggeman effective medium approximation. The optical response of the supracrystal depends on the volume fraction of the nanoparticles and their aspect or size ratio (major/minor axis). All the nanoparticles have the same orientation, and this defines an anisotropic dielectric function of the crystal. As a function of the filling fraction, while keeping the size ratio fixed, the maximum in the extinction spectra along the major and minor axes does not show a significant change. However, for a fixed filling fraction, varying the aspect ratio of the particles induces a shift of several hundred of nanometers in the maximum of the extinction spectra along the major axis and almost no changes along the minor axis. Depending on the aspect ratio and the filling fraction, we show that the supra-crystal has three regimes with different values of an effective plasma frequency.

Plasmon polaritons in cubic lattices of spherical metallic nanoparticles

“…Early studies on the plasmonic properties of near-fieldcoupled metallic nanoparticles focused on 1D chains using a nonretarded model of point dipoles [12][13][14][15], followed by fully-retarded classical approaches applied to 1D [16][17][18][19][20][21][22][23][24][25] and 2D systems [26][27][28][29][30]. Three-dimensional metastructures were also investigated using more approximate approaches such as the Maxwell-Garnett effective medium theory [7] or Bruggeman effective medium theory [31]. In addition to the classical, typically fully numerical treatments, an analytically tractable approach based on a Hamiltonian formalism was recently applied to 1D [32][33][34][35], 2D [36][37][38] and 3D systems [39].…”