Optical responses in conventional metamaterials based on plasmonic metal nanostructures are inevitably accompanied by Joule losses, which obstruct practical applications by limiting resonance quality factors and compromising the efficiency of metamaterial devices. Here we experimentally demonstrate a fully-dielectric metamaterial that exhibits a ‘trapped mode’ resonance at optical frequencies, founded upon the excitation by incident light of anti-parallel displacement currents in meta-molecules comprising pairs of parallel, geometrically dissimilar dielectric nano-bars. The phenomenon is demonstrated in the near-infrared part of the spectrum using silicon, showing that in principle strong, lossless resonant responses are possible anywhere in the optical spectral range.
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