Fig. 1: Schematic illustration of topological states and number transitions.
From: Topological state and number transitions of optical skyrmions upon free-space beam propagation
a Constructing different 2D skrymions by vector projections from S2 Poincaré sphere to R2 plane. And polarization distributions of 2D skyrmionics beams corresponding to three skyrmion types, namely, the Poincaré beams. Ellipse: polarization ellipticity; Red: left hand; Blue: right hand. b The schematic of 2D Stokes skyrmion and skyrmion number transitions upon the propagation of a skyrmionic beam.
