Fig. 1. Schematics of femtosecond laser direct writing platform. (a) Galvanometer processing platform; (b) 3D piezoelectric ceramic displacement processing platform

Fig. 2. Micronano structures prepared by LIPSS on surfaces of different materials. (a) SOI surface grating and its structural color^[46]; (b) micro-nanostructure prepared on surface of 316L stainless steel and its structural color^[47]; (c) LIPISSs in different directions^[48]; (d) LIPISSs with polarization dependence and its structural color^[49]

Fig. 3. Adjustable structure colors prepared on stainless steel (X2CrNiMo17-12-2) and polymer surfaces^[50]. (a) Structural colors produced by LIPSS on surface of stainless steel under different observation angles with white light illumination; (b) change of structural color from green to yellow when stainless steel is stretched in different degrees; (c) change of structural color when polymer is stretched in different degrees

Fig. 4. Structural colors of LIPSS formed at different processing wavelengths and viewing angles ^[51]

Fig. 5. Superhydrophobic structures on different material surfaces. (a) Large-area superhydrophobic surface^[56]; (b) lotus leaf like superhydrophobic microboat^[57]; (c) compound eye inspired multifunctional integration glass^[58]; (d) ice resistance of superhydrophobic structure on PTFE^[59]

Fig. 6. Superhydrophobic structures based on polymer with shape memory property of thermal response^[61]. (a) Physical diagrams of SMP film in initial state and deformation state and after restoration, and SEM images of reversible morphological transformation between original and deformed micro-column arrays; (b) schematic and physical diagrams of liquid transportation in different tracks on surface of SMP micro-column array and self-cleaning effect

Fig. 7. Antireflective structures induced by femtosecond lasers on silicon surface^[66]. (a) SEM image of periodic surface structure induced by femtosecond laser on silicon wafer and different colors when observing silicon wafer at different viewing angles; (b) antireflection test results of total reflection and specular reflection of polarized light at 6° incident angle by structure prepared by FLIPSSs

Fig. 8. Antireflection structures induced by femtosecond laser on fused quartz surface^[67]. (a) Optical photo and SEM image of insect wing and its surface microstructure; (b) optical photo and SEM image of treated fused quartz sheet and its surface microstructure; (c) photo of treated antireflection fused quartz sheet; (d) test results of reflectance of unstructured and single-sided antireflection structure and double-sided antireflection structure from light band to mid infrared light band

Fig. 9. Antireflection structures induced by femtosecond laser on 304 stainless steel surfaces^[68]. (a) SEM images of femtosecond laser-induced icrostructures under different polarization and energy densities; (b) specular reflection characteristics of prepared samples; (c) reflection characteristics of prepared samples in circle band in Fig. 9 (b)

Fig. 10. Subwavelength microstructures fabricated on ZnS by parallel femtosecond laser beams^[69]. (a) Schematic of experimental setup for femtosecond laser parallel processing of subwavelength microstructures; (b) physical diagram of prepared sample; (c) 5×5 light field intensity distribution of focused diffraction pattern; (d) transmission spectra of single-sided structure at different incident angles; (e) transmission spectra of double-sided structure at different incident angles

Fig. 11. Antireflection structures on nickel surface prepared by ethanol assisted femtosecond laser irradiation^[70]. (a) Schematic of experimental setup for one-step assembly of 3D micro-nano cage structure under ethanol assisted femtosecond laser irradiation, irregular microstructure induced by laser in air, laser induced spherical microstructure in distilled water, and 3D micro-nano cage structure induced in ethanol solvent; (b) reflectivity test and physical diagrams of 3D micro-nano cage structures prepared by laser irradiation of nickel surface with different pulse energies

Fig. 12. Fabrication of bioinspired compound eye based on PMMA by femtosecond laser direct writing and thermo-mechanical bending^[78]. (a) Flow chart of preparation of PMMA-based bioinspired compound eye; (b) SEM image of morphology of PMMA-based bioinspired compound eye; (c) optical microscope diagram of imaging of PMMA-based bioinspired compound eye; (d) field angle of PMMA-based bioinspired compound eye

Fig. 13. PDMS based bioinspired compound eye prepared by wet etching assisted femtosecond laser direct writing and lithography^[79]. (a) Flow chart of preparation of PDMS-based bioinspired compound eye; (b) schematic of femtosecond laser direct writing micro-dot array on inclined glass sheet and analysis results of micro-lens deformation; (c) test results of morphology of PDMS-based bioinspired compound eye; (d) optical test results of PDMS-based bioinspired compound eye

Fig. 14. Bioinspired compound eye fabricated by dry etching assisted femtosecond laser direct writing and high-temperature casting of superhard materials^[81]. (a) Flow chart of preparation of glass-based bioinspired compound eye and morphology of bioinspired compound eye; (b) imaging and focusing diagrams of glass-based bioinspired compound eye; (c) field angle of glass-based bioinspired compound eye

Fig. 15. Zoom imaging bioinspired compound eye fabricated by wet etching assisted femtosecond laser direct writing and lithography^[82]. (a) Principle diagrams of design inspiration, preparation process, and zoom imaging of bioinspired compound eye; (b) test diagrams of zoom imaging of bioinspired compound eye