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Here we report the experimental observation of circular dichroism in the second-harmonic field (800–400 nm conversion) generated by self-organized gold nanowire arrays with subwavelength periodicity (160 nm). Such circular dichroism, raised by a nonlinear optical extrinsic chirality, is the evident signature of the sample morphology. It arises from the curvature of the self-assembled wires, producing a lack of symmetry at oblique incidence. The results were compared, both in the optical linear and nonlinear regime, with a reference sample composed of straight wires. Despite the weak extrinsic optical chirality of our samples (not observable by our optical linear measurements), high visibility (more than 50%) was obtained in the second-harmonic generated field.
American Physical Society
Publication date: 
12 Dec 2011

A Belardini, M Centini Larciprete, M Centini, E Fazio, C Sibilia, D Chiappe, C Martella, A Toma, M Giordano, F Buatier De Mongeot

Biblio References: 
Volume: 107 Issue: 25 Pages: 257401
Physical review letters