Observation of toroidal pulses of light

Transverse electromagnetic waves are important carriers of information and energy. In 1996, Hellwarth and Nouchi theoretically identified a radically different, non-transverse type of electromagnetic pulse with a toroidal topology. These pulses, which are propagating counterparts of localized toroidal dipole excitations in matter, exhibit unique electromagnetic wave properties and, so far, have never been experimentally realized and observed. Here we report the generation of such toroidal light pulses in the optical and terahertz regions by the use of tailored nanostructured meta-surfaces. This achievement paves the way for experimental studies of energy and information transfer with toroidal light pulses, their space–time coupling and their light–matter interactions involving anapoles, localized space–time coupled excitations, skyrmions and toroidal qubits, which are of growing interest for the fundamental science of light and applications.