title: High-Quality-Factor Mid-Infrared Toroidal Excitation in Folded 3D Metamaterials.
abstract: With unusual electromagnetic radiation properties and great application potentials, optical toroidal moments have received increasing interest in recent years. 3D metamaterials composed of split ring resonators with specific orientations in micro-/nanoscale are a perfect choice for toroidal moment realization in optical frequency considering the excellent magnetic confinement and quality factor, which, unfortunately, are currently beyond the reach of existing micro-/nanofabrication techniques. Here, a 3D toroidal metamaterial operating in mid-infrared region constructed by metal patterns and dielectric frameworks is designed, by which high-quality-factor toroidal resonance is observed experimentally. The toroidal dipole excitation is confirmed numerically and further demonstrated by phase analysis. Furthermore, the far-field radiation intensity of the excited toroidal dipoles can be adjusted to be predominant among other multipoles by just tuning the incident angle. The related processing method expands the capability of focused ion beam folding technologies greatly, especially in 3D metamaterial fabrication, showing great flexibility and nanoscale controllability on structure size, position, and orientation.
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Collaborative Innovation Center of Quantum Matter, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Collaborative Innovation Center of Quantum Matter, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Du
authors.affiliation: College of Materials Science and Engineering, Beijing University of Technology, Beijing, 100124, China.
authors.forename: Ajuan
authors.initials: A
authors.lastname: Cui
authors.affiliation: The MOE Key Laboratory of Weak Light Nonlinear Photonics, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin, 300071, China.
authors.forename: Zhancheng
authors.initials: Z
authors.lastname: Li
authors.affiliation: Key Laboratory of Space Applied Physics and Chemistry Ministry of Education and Department of Applied Physics, School of Science, Northwestern Polytechnical University, Xi'an, 710129, China.
authors.forename: Yuancheng
authors.initials: Y
authors.lastname: Fan
authors.affiliation: The MOE Key Laboratory of Weak Light Nonlinear Photonics, School of Physics and TEDA Institute of Applied Physics, Nankai University, Tianjin, 300071, China.
authors.forename: Shuqi
authors.initials: S
authors.lastname: Chen
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Collaborative Innovation Center of Quantum Matter, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Wuxia
authors.initials: W
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Collaborative Innovation Center of Quantum Matter, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Li
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, Collaborative Innovation Center of Quantum Matter, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
authors.forename: Changzhi
authors.initials: C
authors.lastname: Gu
keywords: 3D; far-field; folded metamaterials; radiation intensity; toroidal dipoles