Arbitrary orientation and tilt control of topological dark lines driven by magneto-optics

Spatiotemporal optical vortices (STOVs) exhibit transverse orbital angular momentum (OAM) that is perpendicular to the propagation direction of the pulse, presenting significant prospects for applications in optical manipulation, information transmission, and terahertz devices. However, existing STOV generation schemes utilizing photonic crystal plates are limited in their ability to independently and dynamically regulate both the transverse OAM and the topological structure of dark lines. Furthermore, the positions and orientations of these dark lines are typically constrained by the symmetry of the system. This paper proposes and validates a tunable STOV generator based on magneto-optic photonic crystal plates. By introducing the magneto-optical effect of magnetic materials and jointly adjusting the intensity and direction of the applied magnetic field, we have achieved multi-degree-of-freedom control over topological singularities and dark lines. The adjustment of the magneto-optical constant Q facilitates the continuous modulation of the generation frequency of singularities and dark lines. Furthermore, altering the direction of the magnetic field allows for the breaking of the in-plane mirror symmetry, thereby enabling directional inclination and overall offset of dark lines in momentum space. This work provides an effective solution for the active and dynamic control of spatiotemporal vortices, overcoming symmetry constraints on the generation of STOVs and demonstrating significant application potential in integrated terahertz vortex light sources, optical manipulation, and communication fields.