title: Chiral light intrinsically couples to extrinsic/pseudo-chiral metasurfaces made of tilted gold nanowires.
abstract: Extrinsic or pseudo-chiral (meta)surfaces have an achiral structure, yet they can give rise to circular dichroism when the experiment itself becomes chiral. Although these surfaces are known to yield differences in reflected and transmitted circularly polarized light, the exact mechanism of the interaction has never been directly demonstrated. Here we present a comprehensive linear and nonlinear optical investigation of a metasurface composed of tilted gold nanowires. In the linear regime, we directly demonstrate the selective absorption of circularly polarised light depending on the orientation of the metasurface. In the nonlinear regime, we demonstrate for the first time how second harmonic generation circular dichroism in such extrinsic/pseudo-chiral materials can be understood in terms of effective nonlinear susceptibility tensor elements that switch sign depending on the orientation of the metasurface. By providing fundamental understanding of the chiroptical interactions in achiral metasurfaces, our work opens up new perspectives for the optimisation of their properties.
authors.affiliation: Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, Via A. Scarpa 16, 00161 Roma, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Belardini
authors.affiliation: Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, Via A. Scarpa 16, 00161 Roma, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Centini
authors.affiliation: Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, Via A. Scarpa 16, 00161 Roma, Italy.
authors.forename: Grigore
authors.initials: G
authors.lastname: Leahu
authors.affiliation: Centre for Photonics and Photonic Materials, Department of Physics, University of Bath, Bath, BA2 7AY, United Kingdom.
authors.forename: David C
authors.initials: DC
authors.lastname: Hooper
authors.affiliation: Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, Via A. Scarpa 16, 00161 Roma, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Li Voti
authors.affiliation: Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, Via A. Scarpa 16, 00161 Roma, Italy.
authors.forename: Eugenio
authors.initials: E
authors.lastname: Fazio
authors.affiliation: Electro-Optics Program, University of Dayton, Dayton, Ohio 45469, USA.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Haus
authors.affiliation: Electro-Optics Program, University of Dayton, Dayton, Ohio 45469, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Sarangan
authors.affiliation: Centre for Photonics and Photonic Materials, Department of Physics, University of Bath, Bath, BA2 7AY, United Kingdom.
authors.forename: Ventsislav K
authors.initials: VK
authors.lastname: Valev
authors.affiliation: Dipartimento di Scienze di Base ed Applicate per l'Ingegneria, Sapienza Università di Roma, Via A. Scarpa 16, 00161 Roma, Italy.
authors.forename: Concita
authors.initials: C
authors.lastname: Sibilia