Relating localized nanoparticle resonances to an associated antenna problem

TL;DR

This paper unifies the understanding of nanoparticle and nanoantenna resonances by modeling nanoantennas as Fabry-Perot resonators with nanoparticle terminations, enabling easier resonance prediction and tuning.

Contribution

It introduces a unified conceptual framework linking nanoparticle resonances to nanoantenna behavior using Fabry-Perot resonator models.

Findings

Resonance frequencies match nanoparticle quasi-static dipolar resonances.

Resonances occur even with negligible wire length.

The approach allows for easy resonance tuning by modifying nanoparticle terminations.

Abstract

We conceptually unify the description of resonances existing at metallic nanoparticles and optical nanowire antennas. To this end the nanoantenna is treated as a Fabry-Perot resonator with arbitrary semi-nanoparticles forming the terminations. We show that the frequencies of the quasi-static dipolar resonances of these nanoparticles coincide with the frequency where the phase of the complex reflection coefficient of the fundamental propagating plasmon polariton mode at the wire termination amounts to $\pi$. The lowest order Fabry-Perot resonance of the optical wire antenna occurs therefore even for a negligible wire length. This approach can be used either to easily calculate resonance frequencies for arbitrarily shaped nanoparticles or for tuning the resonance of nanoantennas by varying their termination.