Excitation of Surface Plasmon Polaritons by Diffraction-Free and Vector Beams

TL;DR

This paper demonstrates efficient excitation of surface plasmon polaritons using diffraction-free and vector beams, enabling long-range biosensing and integrated plasmonic circuits without complex material modifications.

Contribution

It introduces a novel method of exciting SPPs with various wave packets and polarization states, bypassing the need for material optimization or surface patterning.

Findings

SPPs can be excited by 2D Gaussian and Bessel-Gauss wave packets.

Polarization encoding enhances SPP coupling and selectivity.

Long-range SPP excitation achieved without surface patterning.

Abstract

Surface plasmon polaritons (SPPs) are traditionally excited by plane waves within the Rayleigh range of a focused transverse magnetic (TM) Gaussian beam. Here, we investigate and confirm the coupling between SPPs and two-dimensional Gaussian and Bessel-Gauss wave packets, as well as one-dimensional light sheets and space-time wave packets. We encode the incoming wavefronts with spatially varying states of polarization then couple the respective TM components of radial and azimuthal vector beam profiles to confirm SPP polarization-correlation and spatial-mode selectivity. Our results do not require material optimization or multi-dimensional confinement via periodically corrugated metal surfaces to achieve coupling at greater extents. Hereby, outlining a pivotal, yet commonly overlooked, path towards the development of long-range biosensors and all-optical integrated plasmonic circuits.