Spatiotemporal Optical Vortices with Invariant Radius and Width

The spatiotemporal optical vortices (STOVs) carrying orbital angular momentum (OAM) perpendicular to the propagation direction have attracted increasing interest because they provide an additional optical degree of freedom. However, a few critical problems hinder STOVs in possible applications. These problems include that the radius of STOVs is not constant and keeps growing with an increasing topological charge; high‐order STOVs have many sidelobes; the pulse shape is far from being a perfect circle because the pulse dimensions differ noticeably in the transverse and longitudinal directions. In this work, all these problems are overcome by theoretically and experimentally demonstrate the perfect STOVs with invariant radius and no sidelobes. The 3D reconstruction reveals a perfect single‐ring shape in the spatiotemporal plane, and the spectral interferometry unveils a spatiotemporal spiral phase of topological charge up to 18. This work paves the way for future applications of STOVs in classical and quantum data encryption and transmission, particle manipulation and OAM‐based sensing and measurement.