Light polarization effect on the extinction spectrum of silver nanostructures

The optical properties of metal nanostructures especially the localized surface plasmon resonances (LSPRs) have been intensively investigated in recent times. In this paper, we explore the resonance behavior for various arrangement of silver (Ag) nanostructures characterized by far field optical spectroscopy in the visible and near-infrared regions of the electromagnetic waves. Depending on the light polarization and nanostructure morphology, extinction cross section spectrum displays multipolar resonance modes. Furthermore, plasmonic coupling within the nanostructure results in a strong increase in the optical response magnitude, accompanied by a spectral position redshift. Using transmission electron microscopy (TEM) images, the nanostructures morphologies are redesigned by Comsol Multiphysics. The optical response of the nanostructures recorded from measurements and modeling based on Finite Element Method (FEM) provides a very good agreement. Knowing the optical response of these nanostructures and exploiting the generation of plasmonic field enhancement, opens applications on several domains such as sensors and imaging.