Fig. 1. Schematic diagrams of scalar and vector diffraction integrations and three projection optical paths. (a) Schematic diagram of scalar diffraction integration^[17]; (b) schematic diagram of vector diffraction integration^[17]; (c) objective focus path^[18]; (d) spatial diffraction path^[19]; (e) direct projection path^[20]

Fig. 2. Applications of Bessel beam in laser fabrication. (a) 400 nm-diameter fiber printed by Bessel beam^[59]; (b) mesh structure fabricated by Bessel beam scanning^[59]; (c) tomographic structure of hole drilled by single Bessel beam pulse^[50]; (d) surface and (e) cross section of sapphire nanosieve structure fabricated by Bessel beam^[52]; (f) comparison of different beam generation mechanisms and intensity distributions^[6]; (g) comparison of cross sections of 50 μm thick silicon through-holes processed by different beams^[6]; (h) principle of beam shaping^[60]; (i) cut faces with different pulse delays and glass thicknesses^[60]; (j) white light interferogram and scanning electron microscope (SEM) pattern of circularly polarized Bessel beam machined sapphire sidewall^[61]; (k) sapphire structures cut using Bessel beam^[61]; (l) schematic diagram of sapphire obtained by Bessel beam cutting and pulse train^[62]; (m) sapphire structure cut faces obtained by cutting of Bessel beams with different pulse energies and with polarization direction perpendicular to cutting path^[62]

Fig. 3. Characteristics of needle-shaped beam and its applications in fabrication. (a) Spatial diffraction path and phase design^[44]; (b)(c) micropillar array fabricated by single needle-shaped beam single exposure^[44]; (d) phase and intensity distributions of beams with different focal lengths^[45]; (e) microtube array and (f) cell scaffold fabricated by long focal length beam^[45]; (g) phase and intensity distributions of ultrahigh-aspect-ratio beam^[63]; (h) phase distribution of needle-shaped beam, (i) corresponding normalized axial intensity distribution, and (j) contrast of intensity distributions obtained by numerical simulation and experiment^[64]

Fig. 4. Characteristics of Airy beam and its applications in fabrication. (a) Airy beam cubic phases for generating 1D and 2D Airy beams^[69]; (b) propagation dynamics of finite-energy Airy packet^[69]; using Airy beam to machine (c)(d) diamond and (e)(f) silicon^[70]; (g)(h) hexagonal structures fabricated by ring Airy beam^[73]; (i) microclaw structure fabricated by single exposure of Airy beam with four lobes^[74]

Fig. 5. Applications of multi-focus array in laser fabrication. (a)(b) Fabrication of microlens arrays with different offsets and diameters^[21]; (c) silica close-packed compound microlens array^[30]; (d) sapphire microlens array^[31]; (e) different focus designs and phase and energy distributions^[75]; (f) 3D structures printed in hydrogel^[23]; (g) high-speed printing of functional structure using galvanometer scanner and spatial light modulator^[76]; (h) fabrication of dot matrix using FLCos-SLM^[28]; (i) octahedron lattice obtained by multi-focus parallel scanning processing^[22]

Fig. 6. Generation and modulation methods of multi-focus array and its applications. (a) Holograms of two Bessel beams centered on different parts^[40]; (b) transverse intensity distributions of 3×3 Bessel beam array^[40]; (c) multi-zone plate of fan-shaped subareas and (d) corresponding intensity and polarization distribution^[39]; (e) dartboard phase segmentation and (f) corresponding 3D focus position and polarization distributions^[46]; (g) circular-sectional phase segmentation and (h) multipoint structures obtained by two-photon polymerization processes^[41]; (i)(j) flower-like micro structure printed by multi-focus superposed high-order Bessel beam^[78]; (k) microchannel fabricated by double beam created by Dammann grating^[43]; (l) Dammann grating superimposed with Fresnel phase and (m) corresponding energy distribution of foci^[43]; (n) using multifocal array to write structural color information inside lithium niobate^[80]

Fig. 7. Generation of flat-top beam and its applications in fabrication. (a) Flat-top beams with various shapes and sizes realized by complex amplitude modulation^[13]; (b) micro structures printed by quare flat-top beam^[27]; (c)(d) various microstructures printed by patterned laser^[27]; (e) optimized propagation distance of flat-top beam by phase correction^[49]; (f) percussion drilling on metal foil by flat-top beams with different sizes^[49]

Fig. 8. Generation and fabrication effects of uniform patterned light field. (a) High signal-to-noise ratio achieved by multiple CGHs^[25]; (b) increasing uniformity by multiple CGHs^[25]; (c) decomposing target light field into four interlacing subpatterns and calculating CGHs successively^[24]; (d) enhancing patterning uniformity by increasing subpatterns^[24]; (e) numerically simulated intensity distributions of 3D target fields^[90]; (f) 3D “PKU” pattern polymerized by single exposure and Great Wall polymerized via 1D single scan^[90]

Fig. 9. Surface patterning via SLM. (a) Morphologies of light field modulated by masks of different shapes used in stainless steel drilling ^[91]; (b) star shaped beam generated by combination of binary phase mask and multi-focus CGH^[92]; (c) loading target light field on SLM directly to pattern silicon surface with different stripe orientations^[20]; (d) structured color butterfly pattern processed on silicon surface^[20]

Fig. 10. Vector beam generation and 3D structure printing based on vortex beams. (a) Micro rings printed by annular-vortex beams with different diameters^[93]; (b) C shaped light field generated by helical phase CGH and phase mask^[94]; (c) chiral structures printed by interfering vortex beams^[95]; (d) higher-order vortex beams combined with complex amplitude modulation for efficient printing of helical structures^[96]

Fig. 11. Surface texturing by vector beams. (a) Double peak beam generated via radially polarized light filtered by line polarizer^[100]; (b) nanowire structures on Au film ablated by double peak beam^[100]; drilling on (c) silicon dioxide and (d) silicon surfaces by vector beams^[101]; (e) radially polarized light combined with amplitude modulation for ablation of nanopores on glass undersurface^[102]; (f) spiral structures on stainless steel surface induced by vector beam^[103]; (g) nanoripples on silicon surface induced by different vector beams^[104]

Fig. 12. Different focus shaping and correction methods and corresponding applications in laser fabrication. (a) Structures printed inside As₂S₃ with and without refractive index compensation^[105]; (b) comparison of light fields obtained by various beam shaping methods and (d) comparison of waveguide cross-sections with (first row) and without (second row) beam shaping under different laser repetition frequencies^[107]; different silt phases for (c) beam shaping and (e) waveguide fabrication in LiNiO₃^[108]; (f) comparison of phase light field cross sections with and without aberration correction as well as (h) coupling effect comparison of waveguides in different depths^[109]; (g) comparison of different waveguide mode converters fabricated by phase compensation technique and their effects^[111]; (i)(j) stretched beam for nanograting fabrication in silica^[112]

Fig. 13. Applications of spatiotemporal focusing in laser fabrication. Intensity distributions of 1D multi-focus array (a) orthogonal to and (b) along spatial chirp direction^[113]; (c)(d) time-averaged two-photon intensity distributions; (e) linear scanning writing effect on glass surface^[113]; (f) schematic of spatiotemporal focusing based on DMD dispersion^[9]; (g) lattice structure printed by DMD patterns^[9]