Generating spatiotemporal optical vortices using diffraction gratings operating at high-symmetry points
Phys. Rev. A 114, 033513 – Published 14 September, 2026
DOI: https://doi.org/10.1103/jnjg-4w26
Abstract
Spatiotemporal optical vortex (STOV) pulses are localized electromagnetic wavepackets possessing a phase singularity in the plane containing the propagation direction. Such pulses have a transverse orbital angular momentum oriented perpendicularly to that plane. Here, we develop a general theory of STOV generation by resonant gratings operating at high-symmetry points. By studying the properties of the scattering matrix relating the incident and scattered diffraction channels of the grating, we demonstrate that a perfectly symmetric STOV appears when two particular channels are decoupled from each other and from all other channels at a high-symmetry point. The developed theory both explains why symmetric STOVs appear in several grating geometries proposed earlier and allows one to design new geometries for STOV generation. In particular, we design a grating for semi-guided STOV generation in the Littrow mounting and a grating generating simultaneously a pair of free-space STOVs in diffraction orders. The presented rigorous simulation results based on the Fourier modal method are in perfect agreement with the developed theory.
