Transmission Welding of Glass by Femtosecond Laser: Mechanism and Fracture Strength

Femtosecond laser pulses were focused on the interface of two glass specimens. Proper use of optical and laser processing parameters enables transmission welding. The mor-phology of the weld cross section was studied using differential interference contrast op-tical microscopy. In addition, a numerical model was developed to predict the absorption volumes of femtosecond laser pulses inside a transparent material. The model takes into account the temporal and spatial characteristics and propagation properties of the laser beam, and the transmission welding widths were subsequently compared with the absorp-tion widths predicted by the model. The model can lead to the achievement of a desirable weld shape through understanding the effects of laser pulse energy and numerical aper-ture on the shape of the absorption volume. The changes in mechanical properties of the weld seams were studied through spatially resolved nanoindentation, and indentation fracture analysis was used to investigate the strength of the weld seams. [DOI: 10.1115/1.4005306]