Metamaterials have been the platform for experimental development of a new chapter in electrodynamics devoted to toroidal and anapole modes of excitation and the generation of electromagnetic flying donuts. Electromagnetic toroidal dipoles can be represented as currents flowing on the surfaces of tori. They provide physically significant contributions to the basic characteristics of matter including absorption, dispersion, and chirality. They give rise to dynamic anapoles, illusive non-radiating charge-current configurations. Toroidal excitations also exist in free space as spatially and temporally localized electromagnetic pulses, a topologically complex formation of vortices, propagating at the speed of light and interacting with matter in a way different from conventional electromagnetic transvers pulses. We discuss these recent findings and the role of localized and propagating electromagnetic toroidal excitations in light-matter interactions, spectroscopy and telecommunications.

© 2019 IEEE

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