Focused electromagnetic doughnut pulses and their interaction with interfaces and nanostructures

摘要

We study the propagation properties and light-matter interactions of thefocused doughnut pulses, broadband, single-cycle electromagnetic perturbationsof toroidal topology first described by Hellwarth and Nouchi in 1996. We showhow focused doughnuts are reflected and refracted at planar metallic andvacuum-dielectric interfaces leading to complex distortions of the fieldstructure. We also identify the conditions under which these toroidal pulsesexcite dominant dynamic toroidal dipoles in spherical dielectric particles.