Chirp-driven suppression of spatiotemporal optical vortex breakup in free-space propagation

Spatiotemporal optical vortices (STOVs) have sparked an explosion of interest due to their intrinsic transverse optical angular momentum. It spurred methods of the STOV formation based on the application of phase masks and metasurfaces. In this quest, the obtained specific doughnut-shaped laser pulses suffer from the disintegration into optical lobes under the free-space propagation due to light diffraction. Here, we present a simple remedy to cure this innate flaw. We found that preliminary chirping of the laser pulse prevents the STOV breakup. We supported this analytically and gave the explicit expression of the required chirp value.