Picosecond laser welding of glasses with a large gap by a rapid oscillating scan.

A welding method that utilizes a picosecond laser with a small-scale rapid oscillating scan is presented in this Letter to achieve the welding of glasses with natural stacking contact (gap≈10  μm). The rapid oscillating scan of the laser not only creates enough molten material to fill the gap, but also releases the internal thermal pressure during the welding process. The contraction created by condensation of the welding area can reduce the gap to less than 3 μm, which provides necessary conditions for realizing continuous welding. By using this method, a maximum joint strength up to 64 MPa can be achieved without any defects. The detail mechanism of laser welding with a rapid oscillating scan was revealed in this Letter. This research lays a good foundation for the laser welding of large-gap glass in practical engineering applications.