Coherent Networks of Plasmonic Dipole Domains: Long-Range Optical Coupling of Phase-Correlated Packages of Metallic Nanoparticles

Abstract

Through the use of experimental and numerical techniques, we study coherent networks of plasmonic phase-correlated dipole domains that can spread coherent properties along ultralong distances. The phase-correlated domains occur in regions containing closely packed metallic nanoparticles with random positions, shapes, and sizes. We demonstrate that when such regions are periodically arranged, forming two-dimensional arrays, optical diffraction can coherently excite and align the plasmonic dipoles of the nanoparticles within each region, forming delocalized collective plasmon resonances associated with the in-phase coupling of the dipoles. We study the impact of the number of metallic nanoparticles in each region, determining the limit at which it becomes a phase-correlated dipole domain and establishes coherent interdomain coupling. Our results show how such a coupling can form coherent networks of packages of delocalized states with the same phase information. $\mathrm{Au}$ nanoislands with different packings, sizes, and shapes are considered as experimental models to explore phase-correlated dipole domains and interdomain coupling. The conditions in which the coherent interdomain coupling occurs via parallel or orthogonal hybridization of the Rayleigh anomaly with the delocalized plasmon resonances supported by the domains are explored. The outcomes offer alternative techniques for coherent transport of energy and information, in which phase-correlated dipole domains serve as units with large coherent spatial extension.