Spatiotemporal optical vortices (STOVs) and relativistic optical guiding

We present 3D PIC simulations of the spatiotemporal development of self-guided laser pulses, both circularly and linearly polarized, in a plasma, providing the first evidence of relativistic spatiotemporal optical vortices (STOVs). In prior work studying filamentation of lower intensity (10¹³-10¹⁴ W/cm²) femtosecond pulses in atmosphere, we discovered that circulation of electromagnetic energy density in these self-guided pulses is mediated by the spontaneous formation of spatiotemporal optical vortices (STOVs), the phase circulation of which resides in spacetime [1]. In this work, at intensities 10¹⁹-10²⁰ W/cm², relativistic collapse of an intense laser pulse drives a plasma wave, which generates STOVs by nonlinear phase shear. These STOVs are seen to nucleate at multiple locations on the pulse and undergo vortex “reconnection,” evolving into vortex rings surrounding the pulse to which they are confined. After formation, phase circulation about STOVs is seen to dictate the local electromagnetic energy flux density and delimit self-focusing and diffraction, playing a critical role in relativistic self-guiding of pulses.

[1] N. Jhajj, I. Larkin, E. W. Rosenthal, S. Zahedpour, J. K. Wahlstrand, and H. M. Milchberg, "Spatiotemporal optical vortices," Phys. Rev. X 6, 031037 (2016).