Plasmonic Coupling in Silver Nanoparticle Dimers: 3D-FDTD Simulation Study of Distance-Dependent Optical Response

Authors S. Bardhan, A. Dey, S. Mitra, S. Das , P. Ghosh , Md. A. Mondal
Affiliations

Department of Computer Science and Engineering, Narula Institute of Technology, Kolkata, India
Е-mail papri.ghosh@nit.ac.in
Issue Volume 18, Year 2026, Number 3
Dates Received 20 February 2026; revised manuscript received 22 June 2026; published online 26 June 2026
Citation S. Bardhan, A. Dey, S. Mitra, et al., J. Nano- Electron. Phys. 18 No 3, 03021 (2026)
DOI https://doi.org/10.21272/jnep.18(3).03021
PACS Number(s) 07.05.Tpt, 73.22. – f
Keywords Silver nanoparticles (4) , LSPR (2) , Plasmonic coupling, 3D-FDTD, Meep simulation, Near-field enhancement.
Annotation

Silver nanoparticle dimers show strong distance-dependent plasmonic coupling because localized surface plasmon resonances mix together. This makes them good candidates for optical and sensing applications at the nanoscale. Although experimental and numerical studies have previously examined plasmonic coupling phenomena, a comprehensive and fully reproducible three-dimensional, high-resolution investigation of gap-dependent optical behavior is still lacking. In this study, we conduct an extensive 3D finite-difference time-domain (3D-FDTD) simulation of silver nanoparticle dimers utilizing Meep, concentrating on 50 nm diameter spheres with interparticle gaps varying from 5 nm to 50 nm. Using Meep's built-in dispersive silver model, a broadband excitation source, and a spatial resolution of 0.5 nm, we can accurately measure extinction spectra, resonance shifts, linewidths (FWHM), quality factors, integrated extinction, and near-field intensity distributions. The bonding dipolar plasmon mode shows a red shift that can be measured, going from 690.51 nm at a 50 nm gap to 703.52 nm at narrow gaps. The biggest shift is about 13.01 nm. At small distances, we see strong electromagnetic hotspots, which confirm that plasmonic coupling is stronger. These results give us a quantitative look at how gap-dependent plasmon hybridization works and give us useful design tips for plasmonic sensors, surface-enhanced Raman scattering (SERS) substrates, and nanoscale photonic devices.

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