Generation, Detection and Light-Matter Interactions of Focused Doughnut Pulses

Focused doughnuts are solutions to Maxwell's equations that exist only in the form of short burst of electromagnetic energy propagating in free-space at the speed of light. They are distinguished from transverse waves by a toroidal configuration of electromagnetic fields and strong field components along the propagation direction. Among others, they are of great importance because of the similarities with the toroidal excitations, that were studied extensively at the Optoelectronics Research Centre of the University of Southampton in the past. Their generation could open the way for new spectroscopic methods, due to the peculiar excitations that they create in matter.
In this research project we study, theoretically and experimentally, their generation, detection and interaction with matter. After a theoretical examination of their characteristics, we seek to understand their optical properties for precise manipulation in the laboratory. Their generation seems to be possible via a broadband pulse interaction with a properly engineered metasurface. A number of pulse characterization techniques will be applied in order to test and ?re-tune their generation. Finally, light matter interaction experiments for the excitation of toroidal modes and dynamic anapoles will be designed.