Induced higher order multipolar resonances from interacting scatterers

Abstract

Access to scatterers that offer a specific multipolar response is of utmost importance to design metasurfaces and metamaterials—and, more general, to control light at the nanoscale. While isolated scatterers have been extensively considered, it is interesting to see more clearly whether higher order multipolar resonances can be induced by exploiting the interaction of multiple scatterers. Here, we study the appearance and deterministic control of higher order multipolar resonances in two coupled high permittivity dielectric scatterers by changing their spacing. To disentangle the effects from those of isolated scatterers, we concentrate on the multipolar expansion of only the field that emerges from the interaction. By expanding the contribution of a specific multipole into a series of Lorentzian oscillators, the resonances can be studied clearly and discussed in terms of resonance position, oscillator strength, and damping. The oscillator strength shows an oscillatory behavior depending on the spacing between the scatterers, and we can identify an optimal distance where the oscillator strength is maximal. With that, we disclose new approaches to tailor the optical response from photonic scatterers.