Interaction properties between different modes of localized and propagating surface plasmons in a dimer nanoparticle array

When the peak positions of propagating surface plasmon polaritons (SPPs) and localized surface plasmon resonances (LSPRs) become very close to each other in a single nanoparticle array structure, an anticrossing behavior of the surface plasmon resonances (SPRs) peak positions usually occurs, which can considerably enhance the near-field intensity. We first report on the interaction of two types of SPRs in a dimer nanodisk-SiO2 spacer-gold film hybrid sandwich structure. The anticrossing behavior does not appear always due to various modes of LSPRs in such structures. Moreover, a crossing behavior also appears based on the interaction of SPPs and a longitudinal bonding mode of LSPRs. When the anticrossing behavior occurs, a bandgap that changes only with the array period also appears. This bandgap influences the electric field intensity enhancement not only in the anticrossing behavior but also in the crossing behavior. The electric field intensity distribution properties both in the anticrossing behavior and crossing behavior are discussed with reference to the hybrid properties of the SPPs and LSPRs modes. Furthermore, we report on the occurrence mechanisms of these different behaviors. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.