Surface Modes Competition in Field Enhancement of Quasi 3D Plasmonic Nanostructures

Quasi 3D (Q3D) plasmonic nanostructures are promising devices in biosensing. One of the most popularforms of these structures consists of a metallic film perforated as an array of nanoholes, separated by a gap from ananodisks array. Here, these structures are studied using finite difference time domain (FDTD) method. Simulationresults show three peaks (field enhancement) in the plasmon spectra of nanodisks. These plasmon peaks arises due tointeraction between surface plasmon polaritons (SPPs) on the metallic film surfaces through diffractive grating orderswith localized surface plasmon resonance (LSPR) of nanodisks, or direct interaction between nanodisks and metallicfilm. It will be shown that changing nanoholes radius size affects all plasmon peaks. A competition occurs betweencoupled SPPs modes in exciting LSPR in nanodisks, and hence the field enhancement on nanodisks. A full discussionon the results will be presented.

کلیدواژه ها:

Plasmon ، Grating ، Finite difference time domain ، Nanostructures ، Surface modes