Nature Communications, Published online: 29 July 2026; doi:10.1038/s41467-026-75464-0 The authors demonstrate second- and third-harmonic generation of spatiotemporal optical vortices (STOVs) with topological charges up to 40 at the fundamental frequency, in cascaded crystals. The conservation law of transverse optical angular momentum is established for sum-frequency generation, providing a route…
