Anisotropic Surface Plasmon Polariton Generation Using Bimodal V-Antenna Based Metastructures

TL;DR

This paper demonstrates how V-shaped nanoantennas in a 1D metastructure can generate asymmetric surface plasmon polariton wavefronts with enhanced control, including directional propagation and focusing effects.

Contribution

It introduces a novel use of bimodal V-antenna metastructures to create asymmetric SPP wavefronts with a single line of antennas, expanding wavefront control capabilities.

Findings

Achieved asymmetric SPP wavefronts with different propagation directions.

Demonstrated focusing and diverging SPP wavefronts on opposite sides.

Used near-field scanning optical microscopy for detailed analysis.

Abstract

V-shaped nanoantennas are among the popular choices for the unit element of a metasurface, a nanostructured surface used for its ability to mold and control the wavefront of light. In general, the motivation for choosing the V-antenna as the unit element comes from its bimodal nature, where the introduction of the second mode offers extra control over the scattered wavefronts. Here, through near-field scanning optical microscopy, we study a 1D metastructure comprised of V-antennas in the context of generating asymmetric surface plasmon polariton (SPP) wavefronts. The key point is that the use of the V-antenna allows for the creation of a two-dimensional phase gradient with a single line of antennas, where the extra phase dimension offers additional control and allows for asymmetric features. Two different asymmetries are created: (1) SPP wavefronts that have different propagation directions on either side of the metastructure, and (2) SPP wavefront asymmetry through focusing: one side of the metastructure focuses SPP wavefronts, while the other side has diverging SPP wavefronts.