Issue 8, 2015

Near-field asymmetries in plasmonic resonators

Abstract

Surface-enhanced infrared absorption (SEIRA) spectroscopy exploits the locally enhanced field surrounding plasmonic metamaterials to increase the sensitivity of infrared spectroscopy. The light polarization and incidence angle are important factors for exciting plasmonic nanostructures; however, such angle dependence is often ignored in SEIRA experiments, typically carried out with Cassegrain objectives. Here, the photothermal induced resonance technique and numerical simulations are used to map the distribution and intensity of SEIRA hot-spots surrounding gold asymmetric split ring resonators (ASRRs) as a function of light polarization and incidence angle. The results show asymmetric near-field SEIRA enhancements as a function of the incident illumination direction which, in analogy with the symmetry-breaking occurring in asymmetric transmission, we refer to as symmetry-breaking absorption. Numerical calculations reveal that the symmetry-breaking absorption in ASRRs originates in the angle-dependent interference between the electric and magnetic excitation channels of the resonators’ dark-mode. Consequently, to maximize the SEIRA intensity, ASRRs should be illuminated from the dielectric side at an angle that maximizes the constructive interference of the two excitation channels, (35° for the structures studied here), in place of the Cassegrain objectives. These results can be generalized to all structures characterized by plasmonic excitations that give rise to a surface-normal magnetic moment and that possess an electric dipole.

Graphical abstract: Near-field asymmetries in plasmonic resonators

Supplementary files

Article information

Article type
Paper
Submitted
14 Nov 2014
Accepted
05 Jan 2015
First published
06 Jan 2015

Nanoscale, 2015,7, 3634-3644

Author version available

Near-field asymmetries in plasmonic resonators

V. Aksyuk, B. Lahiri, G. Holland and A. Centrone, Nanoscale, 2015, 7, 3634 DOI: 10.1039/C4NR06755J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements