Lattice plasmon modes in an asymmetric environment: from far-field to near-field optical properties

Plasmonic nanostructures arranged in regular arrays support lattice plasmon modes. Such arrays supporting lattice modes can provide improved platforms in the context of non-linear optics, molecular sensing, plasmon-based lasers, or surface enhanced spectroscopies. These lattice modes are characterized by a reduced linewidth of the resonance and an important improvement in its quality factor. In this work, we discuss the impact of these particular resonances on the far-field plasmonic response, in relation to their near-field optical properties. In particular, our results evidence that for inter-particle distances higher than a critical grating constant, the maximum of near-field enhancement is blue-shifted compared to the far-field localized surface plasmon wavelength, which is the opposite of the usual trend.