Optical properties of Au-Ag nanosphere dimer: Influence of interparticle spacing

In this paper, the extinction and near-field properties of Au-Au, Ag-Ag nanosphere homo-dimer and AuAg nanosphere hetero-dimer were studied by using the discrete dipole approximation method. The relation between extinction and interparticle spacing was investigated under y- polarization (perpendicular to dimer axis) and z-polarization (parallel to dimer axis) incidence. The results show that the both extinction peak position and enhancement factor of electric field are sensitive to interparticle spacing when the dimer is illuminated by z-polarization incidence. For Au-Ag hetero-dimer, double same-intensity extinction peaks in visible band were found by regulating interparticle space under z-polarization incidence, and the experience forum was obtained for realizing the double same-intensity peaks.