Fig. 1. Focusing characteristics of tightly autofocusing beam with “8-type” polarization. (a) Trajectory of “8-type” polarization on Poincaré sphere; (b) intensity and polarization distributions of incident beam; (c1)-(c3) propagation processes of different components, with corresponding focal field intensities insetted; (d) intensity distribution curves of components of focal field

Fig. 2. Intensity and polarization characteristics of focal fields with different polarization orders. (a) Intensity distributions of transverse polarization components; (b) intensity distributions of longitudinal polarization components; (c) distributions of Stokes parameter S₃ of transverse polarization components

Fig. 3. Influence of cross point and base vectors on polarization of focal field. (a)-(b) Changing cross point with base vectors unchanged; (c)-(d) changing base vectors with cross point unchanged. First column: projecting trajectories of polarizations; second to fourth columns: distributions of Stokes parameters S₁, S₂, and S₃ of focal fields

Fig. 4. Influence of incident polarization on peak intensity (I_zmax) and proportion (η) of longitudinal polarization component of focal field. (a) Influence of cross point; (b) influence of base vectors

Fig. 5. Influence of base vectors and cross point on peak intensity (I_zmax) of longitudinal polarization component