Figure 4. Fabrication of multi-microholes by the fs PVOF composed of five identical AV-LP-VFs with m = 1 and a = 1.0 mm, which arrange a face-centered square.

(a) and (b) are two generated PVOFs composed of five radially-polarized fields and five azimuthal-polarized fields, respectively, where the arrows show the SoP configurations. (c) shows the simulated focal ring of any individual AV-LP-VF. (d) is the simulated interference pattern of five individual fields, exhibiting a nested lattice composed of two tetragonal lattices (bright and dark spots). (e) indicates the simulated pattern of the focused PVOF. (c)–(e) have a dimension of 60 × 60 μm². (f) is the SEM image of the multi-microholes fabricated by 50 pulses at a fluence of about 6.9 J/cm².