Demonstration of scattering suppression in retardation-based plasmonic nanoantennas

Michael G. Nielsen, Univ So Denmark
Anders Pors, Univ So Denmark
Rasmus B. Nielsen, Tech Univ Denmark
Alexandra Boltasseva, Birck Nanotechnology Center, Purdue University
Ole Albrektsen, Univ So Denmark
Sergey Bozhevolnyi, Univ So Denmark

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.

Discipline(s)

Engineering | Nanoscience and Nanotechnology