Direct laser interference patterning for scalable ultrashort-pulsed laser welding

• Using laser interference for welding enhances scalability for industrial applications. • A 2-beam direct laser interference patterning setup is optimal for laser welding. • Testing results confirm the suitability of beam interference for laser welding. • Shear strength results are comparable to single-beam laser welding. Direct laser interference patterning (DLIP) utilises the interference from two or more beams for texturing large surfaces at high processing speeds. Using this technique for ultrashort-pulsed (USP) laser welding would aid in scaling this process for industry. We demonstrate the first successful DLIP USP laser welding of fused silica glass to both silicon and to stainless steel. Our results indicate that a 2-beam DLIP configuration is best suited to ensure a successful weld is formed. Shear strength and stress-induced birefringence testing results further demonstrate the suitability of the process.