American Chemical Society
ph500293u_si_001.pdf (691.26 kB)

Macroscopic Layers of Chiral Plasmonic Nanoparticle Oligomers from Colloidal Lithography

Download (691.26 kB)
journal contribution
posted on 2014-10-15, 00:00 authored by Robin Ogier, Yurui Fang, Mikael Svedendahl, Peter Johansson, Mikael Käll
Optical near-field coupling between closely spaced plasmonic metal nanoparticles is important to a range of nanophotonic applications of high contemporary interest, including surface-enhanced molecular spectroscopy, nanooptical sensing, and various novel light-harvesting concepts. Here we report on monolayers of chiral heterotrimers and heterotetramers composed of closely spaced silver and/or gold nanodisks of different heights fabricated through facile hole-mask colloidal lithography. These quasi-three-dimensional oligomers are interesting for applications because they exhibit “hot” gaps and crevices of nanometric dimensions, a pronounced circular dichroism, and optical chirality in the visible to near-infrared wavelength range, and they can be produced in large ensembles (>109) of identical orientation. We analyze the optical properties of the samples based on simulation results and find that the circular dichroism is due to strong near-field coupling and intricate phase retardation effects originating in the three-dimensional character of the individual oligomers.