Fig. 1. Schematic of the generation of optical skyrmions formed by electromagnetic field vectors in the focal region of two pairs of counter-propagating cylindrical vector beams under 4π focal condition. PP1, PP2: homogeneous phase plate with a phase delay of π/2; BS1, BS2: beam splitter; L1, L2: objectives

Fig. 2. Normalized distributions of the components of the Néel-type optical skyrmion formed by electric field vectors in the focal plane. (a)~(b) Radial and longitudinal components of the focused electric field in the focal plane; (c) Angular component of the focused magnetic field in the focal plane; (d) The cross sections of the individual components of the focused electromagnetic field

Fig. 3. Vectorial distributions of the Néel-type optical skyrmion formed by electric field vectors in the focal plane. (a)~(b) Normalized energy density distributions of the focused electric field and magnetic field in the focal plane. The black arrows represent the projections of the electric or magnetic field unit vectors on the focal plane; (c) Three-dimensional vectorial structure of the optical skyrmion formed by electric field vectors within the red circle in (a); (d) Two-dimensional vectorial structure of the focal magnetic field in the central region of (b); (e) Orientations of the electric field unit vectors along the radial direction of the constructed Néel-type optical skyrmion; (f) Variation of θ_xy versus r; (g) Skyrmion numberdensity distribution of the constructed optical skyrmion in the focal plane

Fig. 4. Normalized distributions of the components of the Bloch-type optical skyrmions formed by electromagnetic field vectors in the focal plane. (a)~(b) Angular and the longitudinal components of the focused electric field in the focal plane; (c)~(d) Angular and longitudinal components of the focused magnetic field in the focal plane; (e) Cross sections of the individual components of the focused electromagnetic field

Fig. 5. Vectorial distributions of the Bloch-type optical skyrmions formed by electromagnetic field vectors in the focal plane. (a)~(b) Normalized energy density distributions of the focused electric field and magnetic field in the focal plane. The black arrows represent the projections of the electric or magnetic field unit vectors on the focal plane; (c)~(d) Three-dimensional vectorial structures of the optical skyrmions formed by electromagnetic field vectors within the red circles in (a) and (b); (e)~(f) Orientations of the electric field unit vectors and the magnetic field unit vectors along the radial directions of the constructed Bloch-type optical skyrmions; (g)~(h) Variations of θ_xy versus r; (i)~(j) Skyrmion number density distributions of the constructed optical skyrmions in the focal plane