Near-field mapping of Fano resonances in all-dielectric oligomers

We demonstrate experimentally Fano resonances in all-dielectric oligomers clusters of dielectric particles. We study two structures consisting of a ring of six ceramic spheres with and without a central particle and demonstrate that both structures exhibit resonant suppression of the forward scattering associated with the Fano resonance originated from the excitation of magnetic dipole modes. By employing the near-field measurement techniques, we establish the relation between near-and far-field properties of the Fano resonances and identify directly their origin. We support our findings by an analytical approach based on the discrete-dipole approximation and find an excellent agreement with the experimental data. (C) 2014 AIP Publishing LLC.