Xu, SuSayanskiy, A.Kupriianov, Anton S.Tuz, Vladimir R.Kapitanova, PolinaSun, Hong-BoHan, WeiKivshar, Yuri2020-03-31http://hdl.handle.net/1885/202553The study of toroidal dipole modes has attracted a growing attention due to the specific properties of the toroidal electromagnetic response which differs from more familiar electric and magnetic dipole modes. Herein, toroidal dipole modes generated by metasurfaces composed of trimer clusters of high‐index dielectric particles are observed. Both far‐field transmission measurements and direct near‐field mapping of the electromagnetic fields are performed in microwave experiments, and two distinct types of the toroidal dipole modes are observed in a single geometry of the metasurface design, where the toroidal modes are generated either inside of the three‐particle clusters (the so‐called intra‐cluster toroidal modes) or between the neighboring particles in the clusters (inter‐cluster toroidal modes). A transient response of the toroidal dipole modes excited by a pulse is studied in detail. Since the metasurface is composed of simple dielectric disks without the use of any metallic components, the proposed design can be feasibly scalable to both micro‐ and nanometer‐size dielectric structures, and it can be employed in the flat‐optics platform for realizing the beams shaping and efficient light–matter interaction for multiple hotspot energy localization, nonlinear frequency conversion, and highly efficient trapping of light.Y.S.K. acknowledges support from the Australian Research Council and useful discussions and collaboration with S. Lepeshov and A. Krasnok; S.X. thanks helpful discussions with X.-H. Shi and acknowledges the support from National Natural Science Foundation of China (NSFC) (Grant No. 61805097) and from the Jilin University (Grants Nos. 4190805007B4 and 451180501I11); the fabrication of the metasurface Design ① and its experimental characterization in the ITMO University have been supported by the Russian Science Foundation (Grant Nos. 17-19-01731); H.-B.S. acknowledges support from the National Natural Science Foundation of China (NSFC) (Grant Nos. 61590930, 21473076, 61605055, and 61435005) and National Key R&D Program of China (grant 2017YFB1104300).9 pagesapplication/pdfen-AU© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheimmeta-optics, metasurfaces, subwavelength structures, toroidal dipole modes201910.1002/adom.2018011662019-11-25