title: Demonstration of scattering suppression in retardation-based plasmonic nanoantennas.
abstract: Modifications in scattering strength of and local field enhancement by retardation-based plasmonic nanoantennas when being transformed from straight nanorods to split-ring resonators are investigated experimentally. Scattering properties are characterized with linear reflection and extinction spectroscopy of nanoantenna arrays, whereas local field enhancements are evaluated for individual nanoantennas using two-photon-excited photoluminescence (TPL) microscopy. The linear and nonlinear optical characterizations reveal that the optical response of nanoantennas is determined by the interference of counter-propagating short-range surface plasmon polaritons (SR-SPP) and that the transformation of nanorods into split-rings by bending significantly influences the scattering strength. Importantly, strong suppression of scattering for the fundamental SR-SPP resonance is observed when the bend radius is decreased, a feature that is attributed to the decrease in the nanoantenna electric-dipole response when bending the nanorods. The experimental observations are corroborated with numerical simulations using the finite-element method.
authors.affiliation: Institute of Sensors, Signals and Electrotechnics, University of Southern Denmark, Niels Bohrs Allé 1, DK-5230, Odense M, Denmark. mgni@sense.sdu.dk
authors.forename: Michael G
authors.initials: MG
authors.lastname: Nielsen
authors.forename: Anders
authors.initials: A
authors.lastname: Pors
authors.forename: Rasmus B
authors.initials: RB
authors.lastname: Nielsen
authors.forename: Alexandra
authors.initials: A
authors.lastname: Boltasseva
authors.forename: Ole
authors.initials: O
authors.lastname: Albrektsen
authors.forename: Sergey I
authors.initials: SI
authors.lastname: Bozhevolnyi