Plasmon scattering from single sub-wavelength holes

TL;DR

This study maps and analyzes the scattering of surface plasmon polaritons by single sub-wavelength holes in gold films, revealing the modes involved and their electromagnetic properties with high precision.

Contribution

It provides detailed experimental mapping and quantification of plasmon scattering modes, including the polarizability of holes, aligning with electromagnetic theory.

Findings

Identification of a radial surface wave with isotropic amplitude

Quantification of hole polarizability matching theoretical predictions

Observation of a 38 fs time-delay indicating interaction with a broad resonance

Abstract

We map the complex electric fields associated with the scattering of surface plasmon polaritons by single sub-wavelength holes of different sizes in thick gold films. We identify and quantify the different modes associated with this event, including a radial surface wave with an angularly isotropic amplitude. This wave is shown to arise from the out-of-plane electric dipole induced in the hole, and we quantify the corresponding polarizability, which is in excellent agreement with electromagnetic theory. Time-resolved measurements reveal a time-delay of 38? +/- 18 fs between the surface plasmon polariton and the radial wave, which we attribute to the interaction with a broad hole resonance.