Picosecond Laser Micro-welded Similar and Dissimilar Material

We report the successful picoseconds laser welding of a range of similar and dissimilar materials. The welds are formed by a tightly focused 1030 nm, 5.9 ps, 400 kHz laser system which induces microplasma formation. With suitably well prepared samples the plasma is confined and re-solidifies into a weld. Due to the speed of the interaction time between laser and material the heat affected zone is restricted to a few 100 µm around the weld making it an essentially cold process. We specifically report the capability to weld fused silica, borosilicate and sapphire to aluminium, copper, stainless steel, silicon and silicon carbide. Analysis of material mobility in fused silica welds has been investigated through confocal fluorescent microscopy of an Nd doped sample welded to an undoped sample. The results indicate limited mobility in the head affected zone but high mobility in the microplasma region. While the process requires significant surface preparation (Ra < 60nm) the versatility of the process allows a wide range of materials to be welded with essentially the same laser system.