Fig. 1: 0D singularity geometry.
a 0D singularities in 3D space are isolated points of vanishing intensity in a scalar field E, occurring when the real (blue) and imaginary (red) zero-isosurfaces of E intersect tangentially. b yz cross-sectional phase and (c) intensity profiles of the 0D singularity in (a). The dotted blue and red lines represent the real and imaginary zero-isolines of E on the plane, respectively. d Magnitude of the phase gradient \(\left|\nabla \phi \right|\) in the yz plane, which is dominated by the minus z-directed phase gradient. The phase gradient diverges to infinity at the singularity position.
