Multimode directionality in all-dielectric metasurfaces
  We demonstrate that spectrally diverse multiple magnetic dipole resonances can be excited in all-dielectric structures lacking rotational symmetry, in contrast to conventionally used spheres, disks or spheroids. Such multiple magnetic resonances arise from hybrid Mie-Fabry-P\'{e}rot modes, and can constructively interfere with induced electric dipole moments, thereby leading to novel multi-frequency unidirectional scattering. Here we focus on elongated dielectric nanobars, whose magnetic resonances can be spectrally tuned by their aspect ratios. Based on our theoretical results, we suggest all-dielectric multimode metasurfaces and verify them in proof-of-principle microwave experiments. We also believe that the demonstrated property of multimode directionality is largely responsible for the best efficiency of all-dielectric metasurfaces that were recently shown to operate across multiple telecom bands. 
Yuanqing Yang, Andrey E. Miroshnichenko, Sarah V. Kostinski, Mikhail   Odit, Polina Kapitanova, Min Qiu and Yuri Kivshar
physics.optics