Fig. 1. Flow chart of SLA^[8]

Fig. 2. Schematic diagram of femtosecond laser processing

Fig. 3. Preparation methods of microlens. (a) Schematic diagram of femtosecond laser-assisted dry etching^[24]; (b) schematic diagram of femtosecond laser-assisted wet etching^[25]

Fig. 4. Array of microlenses, virtual focal spots and virtual images of the letters “IP”^[26]

Fig. 5. Schematic of the fabrication process^[27]. (a) An array of laser-exposed craters is produced on BK7 glass by laser irradiation; (b) craters are treated by ultrasonic-assisted HF etching; (c) concave microlens arrays with smooth surfaces are formed; (d) precision glass molding process; (e) separate the chalcogenide glass (ChG) from the mold; (f) convex ChG microlens arrays

Fig. 6. Preparation of concave lens and compound eye. (a) Fabrication scheme of a sapphire concave microlens by DE-FsLM; (b) schematic diagram of fabrication of sapphire concave compound eye template and K9 glass compound eye^[33]

Fig. 7. Topography diagram of ACE components. (a) Surface morphology of ACE component; (b) cross section shape of shell component^[34]

Fig. 8. Schematic diagram of the device^[36]

Fig. 9. Fabrication schematic of cladding waveguides and splitters^[42]

Fig. 10. Non-Abelian braiding of three modes^[44]. (a) Schematic diagram of a G₂G₁ braiding configuration; (b) modulation profiles of the coupling coefficients; (c) experimental results of the G₂G₁ braiding; (d) light-diffraction patterns at the output facet of the G₁G₂ braiding; (e) G₂G₁ braiding coincidence rate; (f) G₁G₂ braiding coincidence rate

Fig. 11. Preparation of photonic crystals in silica and resin^[45]. (a) Reconstructed image of the 2D triangular PhC in silica; (b) 1D, 2D and 3D structures fabricated in resin; (c) optical microscope images of different atomic planes in laser micro-fabricated diamond photonic lattice in glass

Fig. 12. Spatial filtering diagram. (a) Illustration of broadband spatial filtering in chirped PhCs; (b) principal scheme of direct laser writing using Bessel beams^[46]

Fig. 13. Schematic diagram of the 3D NPC fabrication realized through femtosecond laser engineering^[47]

Fig. 14. Experimental results. (a) Reconstruction of a star pattern at SH wave; (b) output power and pattern at SH wave when tuning the fundamental wavelength; (c) experimental results of three-channel QPM-division multiplexing holography^[48]

Fig. 15. Schematic representation of a chirped FBG^[50]

Fig. 16. Etching schematic and fiber cross section. (a) During the point-by-point FBGs etching process, the femtosecond laser pulse focusing diagram; (b) transparent ferrule channel traction coating fiber schematic diagram^[53]; (c) fiber cross-section geometry and bending calculation parameters

Fig. 17. Schematic of experimental setup used to tension the LPFG^[55]

Fig. 18. Morphologies of grating fabricated by different methods^[56]. (a) Bare fiber writing; (b) refractive index matching liquid method; (c) slit method; (d) reflectance spectra of the last two FBGs; (e) grating morphologies (fabricated by refractive index method) observed at different angles

Fig. 19. Inscription strategy for the MCF^[57]. (a) (b) Laser focus scans across the upper core; (c) fiber is rotated; (d) inscription is repeated; (e) all cores are structured

Fig. 20. Microscope photographs of HLFBGs^[58]. (a) Cross-section of the fiber; (b) top view (parallel to the laser beam); (c) side view (perpendicular to the laser beam)