Probing the electrodynamic local density of states with magnetoelectric point scatterers

In a scattering experiment, the induced dipole moments of a magnetoelectric point scatterer in response to driving fields are given by its polarizability tensor α. Its linewidth will be dictated by the local density of optical states (LDOS) at the scatterer’s position. To retrieve the magnetoelectric cross-coupling components of α for an archetypical magnetoelectric scatterer—a split ring resonator—we study the frequency-dependent extinction cross section σ_ext as a function of distance to an interface. Rather than following a purely electric or purely magnetic LDOS, we find a dependence which reflects the interplay of both dipole moments in a “mixed” magnetoelectric LDOS. For a strongly magnetoelectric cross-coupled microwave scatterer, we compare analytical point dipole with finite element method calculations.