title: Symmetry-selective third-harmonic generation from plasmonic metacrystals.
abstract: Nonlinear processes are often governed by selection rules imposed by the symmetries of the molecular configurations. The most well-known examples include the role of centrosymmetry breaking for the generation of even harmonics, and the selection rule related to the rotational symmetry in harmonic generation for fundamental beams with circular polarizations. While the role of centrosymmetry breaking in second harmonic generation has been extensively studied in plasmonic systems, the investigation of selection rules pertaining to circular polarization states of harmonic generation is limited to crystals, i.e., symmetries at the atomic level. In this Letter we demonstrate the rotational symmetry dependent third harmonic generation from nonlinear plasmonic metacrystals. We show that the selection rule can be imposed by the rotational symmetry of metacrystals embedded into an isotropic organic nonlinear thin film. The results presented here may open new avenues for designing symmetry-dependent nonlinear optical responses with tailored plasmonic nanostructures.
authors.affiliation: School of Physics & Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom and Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong.
authors.forename: Shumei
authors.initials: S
authors.lastname: Chen
authors.affiliation: School of Physics & Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom and Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong.
authors.forename: Guixin
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Physics, University of Paderborn, Warburger Straße 100, D-33098 Paderborn, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Zeuner
authors.affiliation: Department of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong.
authors.forename: Wing Han
authors.initials: WH
authors.lastname: Wong
authors.affiliation: Department of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong.
authors.forename: Edwin Yue Bun
authors.initials: EY
authors.lastname: Pun
authors.affiliation: Department of Physics, University of Paderborn, Warburger Straße 100, D-33098 Paderborn, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Zentgraf
authors.affiliation: Department of Physics, Hong Kong Baptist University, Kowloon Tong, Hong Kong.
authors.forename: Kok Wai
authors.initials: KW
authors.lastname: Cheah
authors.affiliation: School of Physics & Astronomy, University of Birmingham, Birmingham B15 2TT, United Kingdom.
authors.forename: Shuang
authors.initials: S
authors.lastname: Zhang