title: Influence of cross sectional geometry on surface plasmon polariton propagation in gold nanowires.
abstract: We investigated the effects of cross sectional geometry on surface plasmon polariton propagation in gold nanowires (NWs) using bleach-imaged plasmon propagation and electromagnetic simulations. Chemically synthesized NWs have pentagonally twinned crystal structures, but recent advances in synthesis have made it possible to amplify this pentagonal shape to yield NWs with a five-pointed-star cross section and sharp end tips. We found experimentally that NWs with a five-pointed-star cross section, referred to as SNWs, had a shorter propagation length for surface plasmon polaritons at 785 nm, but a higher effective incoupling efficiency compared to smooth NWs with a pentagonal cross section, labeled as PNWs. Electromagnetic simulations revealed that the electric fields were localized at the sharp ridges of the SNWs, leading to higher absorptive losses and hence shorter propagation lengths compared to PNWs. On the other hand, scattering losses were found to be relatively uncorrelated with cross sectional geometry, but were strongly dependent on the plasmon mode excited. Our results provide insight into the shape-dependent waveguiding properties of chemically synthesized metal NWs and the mode-dependent loss mechanisms that govern surface plasmon polariton propagation.
authors.affiliation: Department of Chemistry, ‡Department of Physics and Astronomy, and §Department of Electrical and Computer Engineering, Laboratory for Nanophotonics, Rice University , Houston, Texas 77005, United States.
authors.forename: Scott
authors.initials: S
authors.lastname: Nauert
authors.forename: Aniruddha
authors.initials: A
authors.lastname: Paul
authors.forename: Yu-Rong
authors.initials: YR
authors.lastname: Zhen
authors.forename: David
authors.initials: D
authors.lastname: Solis
authors.forename: Leonid
authors.initials: L
authors.lastname: Vigderman
authors.forename: Wei-Shun
authors.initials: WS
authors.lastname: Chang
authors.forename: Eugene R
authors.initials: ER
authors.lastname: Zubarev
authors.forename: Peter
authors.initials: P
authors.lastname: Nordlander
authors.forename: Stephan
authors.initials: S
authors.lastname: Link