Fig. 3: Schematic of the experimental apparatus.
A chirped pulse from the laser source splits into a signal pulse and a reference pulse. The signal pulse transforms to a spatiotemporal vortex (STOV) pulse after a 2D pulse shaper. The spatiotemporal vortex is stretched along the vortex line and is then converted into a toroidal vortex through an afocal conformal mapping system. The toroidal vortex is characterized by interference with the dechirped reference pulse.
