Coupled dipole approximation across the Γ-point in a finite-sized nanoparticle array

We study the response of a finite-sized nanoparticle array to an incident field in the vicinity of the Γ-point of the lattice. Using the coupled dipole approximation, we find that the dipole distributions can be strongly inhomogeneous and that strong modulations appear as the energy is above the Γ-point. We highlight how this is reflected in real-space extinction efficiencies as well as in radiation patterns from the finite-sized array. This article is part of the themed issue ‘New horizons for nanophotonics’.