Fabrication of crescent-shaped optical antennas

Metal crescent-shaped nanoparticles (see Figure) that are expected to be efficient optical antennas with highly enhanced and localized near-fields are described. The particle-fabrication process combines colloidal templating, metal-film deposition, and ion-beam milling. The crescents exhibit multiple plasmon resonances in the visible and near-infrared that are of the same type as have been proposed for the development of an effective left-handed material.