Charge reservoir as a design concept for plasmonic antennas

TL;DR

This paper investigates the role of a charge reservoir in plasmonic antennas, revealing that larger charge reservoirs lead to increased radiative losses and consequently lower field enhancement, challenging assumptions about maximizing charge for better performance.

Contribution

It introduces the concept of a charge reservoir as a key design element in plasmonic antennas and analyzes its impact on field enhancement and radiative losses.

Findings

Large charge reservoirs increase radiative losses.

Large charge reservoirs do not necessarily lead to higher field enhancement.

Radiative losses dominate the performance limitations of plasmonic antennas.

Abstract

Plasmonic antennas exploit localized surface plasmons to shape, confine, and enhance electromagnetic fields with subwavelength resolution. The field enhancement is contributed to by various effects, such as the inherent surface localization of plasmons or the plasmonic lightning-rod effect. Inspired by nanofocusing observed for propagating plasmons, we test the hypothesis that plasmonic antennas with a large cross-section represent a large charge reservoir, enabling large induced charge and field enhancement. Our study reveals that a large charge reservoir is accompanied by large radiative losses, which are the dominant factor, resulting in a low field enhancement.