Observation of helical pulses

Ultrafast spatiotemporal vortex pulses constitute a category within spatiotemporal topological waves. Nevertheless, the experimental realization of helical pulses single or few cycle short vortex pulses characterized by space time nonseparability remains elusive to date. Here, we introduce two complementary methods for experimentally generating such space time nonseparable helical pulses (SNHPs) in the optical and microwave spectral regimes. We achieve few cycle quasi linearly polarized SNHPs by decomposing the optical toroidal pulses into their polarization components. We also generated single cycle nontransverse SNHPs directly from a microwave ultrawideband spiral emitter. These approaches enable the experimental realization of SNHPs and provide a platform for further investigation into their properties and applications, such as nontrivial light-matter interactions and optical communications.