Circular Optical Nanoantennas: An Analytical Theory

TL;DR

This paper presents an analytical model for the resonance behavior of circular optical nanoantennas made of stacked homogeneous discs, enabling precise tuning without fitting parameters.

Contribution

The authors develop a self-contained analytical theory for circular nanoantennas based on surface plasmon phase accumulation and reflection, eliminating the need for fitting.

Findings

Excellent agreement with rigorous simulations

Model allows tuning by changing stack composition

Provides a simple Fabry-Perot resonator explanation

Abstract

An entirely analytical theory is provided for describing the resonance properties of optical nanoantennas made of a stack of homogeneous discs, i.e. circular patch nanoantennas. It consists in analytically calculating the phase accumulation of surface plasmon polaritons across the resonator and an additional contribution from the complex reflection coefficient at the antenna termination. This makes the theory self-contained with no need for fitting parameters. The very antenna resonances are then explained by a simple Fabry-Perot resonator model. Predictions are compared to rigorous simulations and show excellent agreement. Using this analytical model, circular antennas can be tuned by varying the composition of the stack.