Influence of Gap and Orientation on the Optical Properties of Plasmonically Coupled Nanorod Dimers

Plasmonic nanorods are one of the foundational building blocks in nanophotonics, creating surface plasmon resonances that enable strong near-field enhancement and light-bending applications. The coupling between two nanorods depends on whether there is an interparticle gap, the size of this gap, and the orientation of the rods relative to each other. These factors influence the absorbance spectra and the distribution and magnitude of the enhanced electric fields. In this work, we systematically investigate how the gap and angle between nanorod dimers affect the absorbance, the localized enhanced electric field, and plasmonic coupling of the nanorod dimers. We investigate nanorods that are joined together and how the angle between these rods affects their optical properties. Using the finite element method, we can simulate how the absorbance and the electric field evolve as the two nanorods transition from parallel to perpendicular orientation while increasing or removing the gap between them. Models will also show charge distributions, revealing insight into the nanoscale plasmonic behavior. We found the absorbance spectra shift towards larger wavelengths as the gap increases, while the spectra shift towards smaller wavelengths as the nanorods become parallel.