GOLD PLASMONIC ARRAY STRUCTURES FOR SENSING APPLICATIONS

Abstract

This article is devoted to the theoretical study of the plasmonic properties of periodically arranged arrays of gold nanoparticles. The Comsol Multiphysics software, which is based on the finite element method, was used to build 3D numerical models for the simulation and conduct research. In this work the electric field distribution and optical characteristics of the spherical gold nanoparticles array were studied. Individual localized surface plasmon resonance modes are influenced when metallic nanoparticles are in the close proximity and as a result the electric near- fields can couple, resulting in a new hybrid mode. We mainly focused here on the investigation of two crucial questions, particularly, influences of the gap between the nanoparticles and the refractive index of the surrounding medium on the resulting optical response of the gold nanoparticles arrays. The array of periodically arragement gold nanoparticles is characterized by an enhanced local electric field between the nanoparticles, which is inversely proportional to the gap between the particles. The field strength and optical properties (reflection, transmission, and absorption) can be conveniently manipulated by changing the gap between particles. In additional, their potential applications as sensetive plasmonic sensors element have been considered. The studied structure has a significant potential for practical applications due to its wide range of the operating wavelengths and ease of the high-throughput fabrication. In the course of the study, it was established that the change in the distance between the surface of nanoparticles by 1 nm leads to a significant shift in the spectral transmission and reflection curves on the spectral range. In addition, these studies showed that an increase in the distance between the surfaces of nanoparticles leads to the decrease in the near-field interaction between gold nanoparticles in the array. Therefore, the obtained results can be successfully used in the manufacture of highly sensitive plasmon sensors with the possibility of controlling the sensitivity and the working spectral range.