Fig. 1. Schematic diagrams for laser welding and shear strength testing. (a) Schematic diagram for femtosecond laser welding; (b) schematic diagram for scanning pattern; (c) schematic diagram for shear strength testing

Fig. 2. Thermal physical parameters of 304 stainless steel. (a) Thermal conductivity k; (b) specific heat capacity c_p; (c) density ρ

Fig. 3. Femtosecond laser welding model and model meshing. (a) Geometric model for femtosecond laser welding; (b) model meshing

Fig. 4. Temperature simulation results. (a) Logarithmic horizontal time distribution of electron temperature; (b) linear abscissa time distribution of electron temperature; (c) logarithmic horizontal time distribution of lattice temperature; (d) linear abscissa time distribution of lattice temperature

Fig. 5. Welds morphology under different laser single-pulse energy. (a) Top view of the sample before separation; (b) welds on 304 stainless steel side; (c) welds on silica glass side

Fig. 6. SEM morphology of spot structures of weld. (a) On 304 stainless steel side, magnified 10000 times; (b) on 304 stainless steel side, magnified 30000 times; (c) on silica glass side, magnified 10000 times; (d) on silica glass side, magnified 30000 times

Fig. 7. Shear strength of welding samples with different laser single-pulse energies

Fig. 8. SEM morphology and EDS analysis result of weld. (a) Morphology of weld cross-section; (b) EDS line scanning of weld cross section; (c) morphology of 304 stainless steel weld; (d) EDS line scanning of 304 stainless steel weld; (e) morphology of single weld of 304 stainless steel; (f) element Si distribution; (g) morphology of silica glass weld; (h) element Fe distribution

Fig. 9. XRD patterns and Roman spectra before and after laser welding. (a) XRD pattern of 304 stainless steel; (b) XRD pattern of silica glass; (c) Raman spectra of silica glass