Arresting the singularity splitting of spatiotemporal optical vortices via electromagnetically induced transparency.

A high-order spatiotemporal optical vortex (STOV) singularity generally splits into multiple first-order ones upon propagation. Here, we demonstrate the arrest of this splitting via electromagnetically induced transparency. This is achieved by establishing the condition for diffraction-dispersion balance; solving this condition yields the specific system parameters that arrest the splitting. These solutions, located on the red-detuned side of absorption peaks, correspond to anomalous group-velocity dispersion and normal second-order loss dispersion. With the splitting arrested, we further characterize the spatiotemporal drift dynamics of the STOV singularity by deriving its drift trajectory and velocity. This drift, driven by first-order loss dispersion, exhibits a chiral asymmetry in direction dictated by the sign of the spatiotemporal topological charge.