Improved Femtosecond\nLaser Welding of Nonoptical Contact\nGlass by Pressure and a Water Intermediate Layer

Ultrafast laser welding has emerged as a significant\ntechnology\nfor the joining of transparent materials and has been extensively\nresearched for the welding of glass materials in recent years. However,\nachieving a robust connection requires optical contact between the\nsamples during laser processing, which complicates the welding process\nand increases its cost. To achieve high-strength welding of glass\nsamples without optical contact, the samples are typically pressed\ntogether to minimize the gap, allowing the molten materials to completely\nfill it. In this study, two approaches are employed to facilitate\nhigh-strength welding of silica glasses: femtosecond (fs) laser welding\nwith the assistance of pressure using a fixture and femtosecond laser\nwelding aided by a water intermediate layer. The welding quality achieved\nby both methods is thoroughly examined and compared. The findings\nreveal that femtosecond laser welding with water assistance outperforms\nother methods in terms of welding uniformity and quality. Furthermore,\nthe principle behind achieving high-quality welding is discussed to\nelucidate the success of this method.