Interacting plasmonic nanostructures beyond the quasi-static limit: a "circuit" model

Area of Science:

• Plasmonics and Nanophotonics
• Computational Electromagnetics
• Condensed Matter Physics

Background:

• Interactions between individual plasmonic nanoparticles significantly influence composite structure resonances.
• Understanding these interactions is key to designing advanced plasmonic devices.
• Existing models may not fully capture the intricate coupling dynamics.

Purpose of the Study:

• To develop and demonstrate a modified circuit model for analyzing plasmonic nanoparticle coupling.
• To apply this model to a specific dolmen-like nanostructure.
• To show how circuit analysis techniques can be adapted for plasmonic systems.

Main Methods:

• Utilized the full-wave eigenmode expansion method (EEM) to extract eigenmodes and eigenvalues.
• Reduced electromagnetic interactions to mode interactions using the reaction concept.
• Constructed an equivalent circuit model by identifying the driving voltage source from incident light.

Main Results:

• The coupling between plasmonic structures was successfully captured by the modified circuit model.
• Mode interactions were summarized in a coupling matrix.
• Hybridization of plasmonic modes within the nanostructure was analyzed.
• An equivalent of Thévenin's theorem was derived for nanostructures.

Conclusions:

• The proposed circuit model provides a powerful framework for analyzing plasmonic structures.
• Circuit analysis techniques can be effectively repurposed for plasmonics.
• The model facilitates a clear explanation of phenomena such as Fano resonance.