Two-photon fabrication of three-dimensional metallic nanostructures for plasmonic metamaterials

We propose a novel laser fabrication technique based on two-photon-induced reduction of metal ions for 3D metallic micro/nanostructures. Electrically conductive silver nanostructures with arbitrary 3D shape are demonstrated. By introducing dopant surfactant molecules, which prohibit unwanted metal growth, we demonstrate considerable improvement of the reduction properties to achieve a spatial resolution down to 120 nm. Plasmonic metamaterials fabricated using this technique exhibit magnetic resonances with negative permeability at far-infrared frequencies.