Experimental measurements of fundamental and high-order spoof surface plasmon polariton modes on ultrathin metal strips

TL;DR

This paper experimentally and numerically investigates fundamental and high-order spoof surface plasmon polariton modes on ultrathin metal strips, providing detailed near-field measurements and dispersion relations.

Contribution

It presents the first direct experimental measurement of near-field distributions and dispersion curves for both fundamental and second-order spoof SPP modes on ultrathin metal strips.

Findings

Measured dispersion curves agree with numerical simulations.

Both fundamental and second-order modes are characterized.

Near-field distributions reveal subwavelength field confinement.

Abstract

Propagation of spoof surface plasmon polaritons (spoof SPPs) on comb-shaped ultrathin metal strips made of aluminum foil and printed copper circuit are studied experimentally and numerically. With a near field scanning technique, electric field distributions on these metal strips are measured directly. The dispersion curves of spoof SPPs are thus obtained by means of Fourier transform of the field distributions in the real space for every frequency. Both fundamental and second order modes are investigated and the measured dispersions agree well with numerical ones calculated by the finite element method. Such direct measurements of the near field characteristics provide complete information of these spoof SPPs, enabling full exploitation of their properties associated with the field confinement in a subwavelength scale.