The role of surface plasmon polaritons in the optical response of a hole pair

TL;DR

This paper investigates how surface plasmon polaritons influence the optical response of a simple hole pair in a metal film, revealing interference effects driven by SPPs through a first-principles model.

Contribution

It introduces a parameter-free SPP interference model based on Maxwell's equations to explain the optical behavior of a hole pair.

Findings

Interference pattern governed by SPP re-illumination and impedance effects

Constructive and destructive interference depend on phase differences

Model provides fundamental understanding without fitting parameters

Abstract

The optical emittance of a hole pair perforated in an opaque metal film is studied from first-principles using the coupled-mode method. The geometrical simplicity of this system helps to understand the fundamental role played by surface plasmon polaritons (SPPs) in its optical response. A SPP interference model without fitting parameters is developed from the rigorous solution of Maxwell's equations. The calculations show that the interference pattern of the hole pair is determined by two scattering mechanisms: (i) re-illumination of the holes by the in-plane SPP radiation and (ii) an effective impedance depending on the single-hole response. The conditions for constructive and destructive interference only depend on the phase difference provided by each of the two scattering mechanisms.