Details

Autor(en) / Beteiligte

• Esposito, Marco
• Tasco, Vittorianna
• Cuscunà, Massimo
• Todisco, Francesco
• Benedetti, Alessio
• Tarantini, Iolena
• Giorgi, Milena De
• Sanvitto, Daniele
• Passaseo, Adriana

Titel

Nanoscale 3D Chiral Plasmonic Helices with Circular Dichroism at Visible Frequencies

Ist Teil von

• ACS photonics, 2015-01, Vol.2 (1), p.105-114

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2015

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The nanoscaling of metamaterial structures represents a technological challenge toward their application in the optical frequency range. In this work we demonstrate tailored chiro-optical effects in plasmonic nanohelices, by a fabrication process providing a nanometer scale control on geometrical features, that leads to a fine tuning of operation band even in the visible range. Helicoidal 3D nanostructures have been prototyped by a bottom-up approach based on focused ion and electron beam induced deposition, investigating resolution limits, growth control and 3D proximity effects as a function of the interactions between writing beam and deposition environment. The fabricated arrays show chiro-optical properties at the optical frequencies and extremely high operation bandwidth tailoring dependent on the dimensional features of these 3D nanostructures: with the focused ion beam we obtained a broadband polarization selection of about 600 nm and maximum dissymmetry factor up to 40% in the near-infrared region, while with the reduced dimensions obtained by the focused electron beam a highly selective dichroic band shifted toward shorter wavelengths is obtained, with a maximum dissymmetry factor up to 26% in the visible range. A detailed finite difference time domain model highlighted the role of geometrical and compositional parameters on the optical response of fabricated nanohelices, in good agreement with experimental results.