FEM Simulation For Surface Plasmon Resonance Of Metallic Nanoparticles

The synthesis methods of Au or Ag nanocube, nanobox, nanocage and naoframehave been developed in the past decade. Recently, the techniques of using nanocubeas building block to assemble nanostructures (e.g. dimer or chain) have beendeveloped using the polymer or DNA binding. Since this bottom-up approachbecomes applicable, we are motivated to study the optical properties (scattering andabsorption) of1D,2D and3D assemblies of Au nanoboxes interacting with visiblelight in this thesis. The nanobox is a nanocube with a cubic cavity inside. Thecommercial package of Ansoft HFSS, based on the finite element method, is usedtosimulate and analyze the plasmonic behaviors of these assemblies.For the1D assemblies (a linear array) of nanoboxes, our results show that thefundamental plasmon mode is red-shifted as the number of nanoboxes increases. Inaddition, the plasmon mode of a dimer is red-shifted as the gap decreases. The Fanoresonance in the plasmon mode of a heterogeneous dimer is observed, due to thebroken symmetry.For the2D assemblies (a plane array) of nanoboxes, the trimer (triple)andtetramer (quadruple) structures are studied. The2D assemblies show versatilemultiple modes. For example, five configurations of the tetramer (tetris structure)exhibit different plasmon modes as irradiated by different-polarized plane waves. Inparticular, when the symmetry of the2D assemblies is broken, the Fano resonanceand dip are obviously observed.For the3D assemblies (a solid array) of nanoboxes, we find that their plasmonmodes are more complicated than those of the1D and2D assemblies.In summary, our results illustrate that the plasmon modes of a1D,2D and3Dnanobox-cluster assembly are tunable by tailoring the configuration to manipulatelight on demand.