Mechanisms governing resonant shifts and resilience in optical responses of plasmonic hole arrays

TL;DR

This paper investigates the optical responses of plasmonic hole arrays, comparing simplified analytical models with finite element simulations to understand resonant shifts and resilience in their transmission spectra.

Contribution

It introduces a numerical FEA approach for accurately modeling cylindrical hole arrays and compares it with a simple analytical model to identify mode origins.

Findings

Finite element analysis effectively models periodic hole arrays.

Oblique incident light can alter SPP momentum.

Transmission spectra depend on surrounding dielectric index.

Abstract

This report concerns with the theoretical studies of SPP Bloch waves in arrays of cylindrical holes. Most analytical solutions are simplified, approximate and fitted, thus leading to wrong design parameters. A rigorous analytical solution that can accurately predict the desired dimensions associated with hole arrays is complex to derive. Finite element analysis (FEA), on the other hand, offers extensive capabilities for modelling and simulating the response of periodic structures such as that of an infinite array of holes. In this chapter, a square array of cylindrical holes is modelled numerically. A simple analytical model is presented (not for design purposes) only to identify the origin of the alleged (1,1) and (0,2) modes and the results are compared to the numerical ones. Changes in the transmission spectrum vs the refractive index of the surrounding dielectric when illuminated with a linearly polarized light at normal incidence is studied. Circumstances in which an obliquely incident light changes to the SPP momentum are also identified.