Welding of glass and single crystal graphite film using a high repetition fs laser

In this paper, we successfully welded an ordinary glass and a single crystal graphite film without visible cracks by employing a high repetition femtosecond laser. The tensile strength of two welding samples exceeds those of the original films. Based on the SEM-EDS data and the Raman spectra data, two types of plasma welding regions can be clearly discriminated. The welding mechanism can be attributed to the mixture of graphite plasma and glass plasma and their resolidification. The energy density of single pulse at the interface is the most dominant factor because of this welding mechanism. From the Raman spectra data of the rear surface of the 20 μ m sample, how the shock wave influences the configurations of the C–C bonds in the graphite film can also be studied. Those results are helpful in understanding the dynamics of femtosecond laser welding and quickly optimizing laser parameters.