Direct welding of diamond and glass using burst mode femtosecond pulses

In current research, achieving a strong connection of dissimilar materials with significantly different thermophysical properties remains a formidable challenge. This paper presents for what we believe to be the first time the strong bonding of single-crystalline diamond and fused silica glass by femtosecond laser direct writing, which was achieved under the condition of non-optical contact. The micromorphology and elemental distribution of the welding region were characterized. The results revealed that the solidification of molten silica ejected from the glass substrate fills the gaps between diamond and glass, which could be the primary reason for the achieved connection under burst mode femtosecond laser irradiation. Meantime, the slight ablation and laser-induced periodic surface structures (LIPSSs) were observed on the diamond surface. Furthermore, the influence of the laser processing parameters on the welding strength was investigated, with the highest shear strength recorded in the shear test being 14.1 MPa.