Governing role of spatiotemporal optical vortex phase in interference photoelectron momentum distributions

We present numerical investigation on interference bands and the embedded fine interference fringes in the photoelectron momentum distributions (PMDs) induced from hydrogen ionization by intense spatiotemporal optical vortex (STOV) pulse. The simulation results show that the momentum bands in the coordinate-resolved PMDs are oppositely tilted for opposite topological charges of a STOV pulse, with the band separation in energy in approximately accordance with the multiphoton ionization nature. The fine fringes embedded in the momentum bands are deciphered with the governing role of the classical action phase accumulated for the STOV pulse spanning the singularity along the temporal direction. In addition, we propose an intuitive picture of double multi-slits interference for understanding the interference characteristics of the PMDs initiated by the STOV pulse. Graphical abstract