title: Triple-helical nanowires by tomographic rotatory growth for chiral photonics.
abstract: Three dimensional helical chiral metamaterials resulted in effective manipulation of circularly polarized light in the visible infrared for advanced nanophotonics. Their potentialities are severely limited by the lack of full rotational symmetry preventing broadband operation, high signal-to-noise ratio and inducing high optical activity sensitivity to structure orientation. Complex intertwined three dimensional structures such as multiple-helical nanowires could overcome these limitations, allowing the achievement of several chiro-optical effects combining chirality and isotropy. Here we report three dimensional triple-helical nanowires, engineered by the innovative tomographic rotatory growth, on the basis of focused ion beam-induced deposition. These three dimensional nanostructures show up to 37% of circular dichroism in a broad range (500-1,000 nm), with a high signal-to-noise ratio (up to 24 dB). Optical activity of up to 8° only due to the circular birefringence is also shown, tracing the way towards chiral photonic devices that can be integrated in optical nanocircuits to modulate the visible light polarization.
authors.affiliation: National Nanotechnology Laboratory-NNL, CNR-IMIP, VIA Arnesano, 73100 Lecce Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Esposito
authors.affiliation: National Nanotechnology Laboratory-NNL, CNR-IMIP, VIA Arnesano, 73100 Lecce Italy.
authors.forename: Vittorianna
authors.initials: V
authors.lastname: Tasco
authors.affiliation: National Nanotechnology Laboratory-NNL, CNR-IMIP, VIA Arnesano, 73100 Lecce Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Todisco
authors.affiliation: National Nanotechnology Laboratory-NNL, CNR-IMIP, VIA Arnesano, 73100 Lecce Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Cuscunà
authors.affiliation: Università di Roma La Sapienza, Dip. SBAI, via Scarpa 16, 00161 Roma, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Benedetti
authors.affiliation: National Nanotechnology Laboratory-NNL, CNR-IMIP, VIA Arnesano, 73100 Lecce Italy.
authors.forename: Daniele
authors.identifier: 0000000238318829
authors.initials: D
authors.lastname: Sanvitto
authors.affiliation: National Nanotechnology Laboratory-NNL, CNR-IMIP, VIA Arnesano, 73100 Lecce Italy.
authors.forename: Adriana
authors.initials: A
authors.lastname: Passaseo