Dual-plasmonic architectures: unraveling coupling dynamics between nanoparticle chains and nanoantennas

Abstract The manipulation of plasmonic coupling in hybrid nanostructures, integrating nanoparticles and nanoantennas, offers a promising avenue for next-generation optical metamaterials with enhanced nonlinearities, multiple-resonance responses, and spectral selectivity/tunability. While prior studies have focused on discrete nanoparticle chains or continuous nanostructures, the interplay between capacitive and conductive coupling in hybrid systems remains underexplored. Here, we employ finite-integration simulations to investigate the optical response of metamaterials composed of gold nanoparticle chains and nanobars across various geometrical configurations. Our results reveal distinct plasmonic modes, including localized surface plasmon resonances (LSPRs), surface lattice resonances, and charge transfer plasmon resonances (CTPRs), whose spectral features and intensities are highly tunable via particle size and the vertical layer ordering. Notably, hybrid configurations exhibit emergent behaviors such as dual-peak infrared resonances arising from LSPR-CTPR hybridization and selective mode suppression driven by interfacial charge dissipation. Furthermore, reducing nanoparticle size within fixed-length chains induces anomalous red shifts in LSPRs and CTPRs, attributed to enhanced capacitive coupling. These findings advance the understanding of plasmonic hybridization and provide design guidelines for novel dual-plasmonic materials with potential applications in tunable photonics and enhanced sensing.