Picosecond laser welding of glass with large gap

The welding of glass using ultrashort laser pulse has attracted much attention due to its potential applications in fields such as solar cells, implanted microelectronics, OLED, MEMS, microsensors and so on. However the optical contact which requires a distance between two glasses less than 100 nm is a very harsh requirements in practical engineering applications. A welding method of glass, which adopts bursts sequences of ultrashort laser pulses oscillated in a small region to react more glass material and release heat stress gently, is presented in this paper. In this way, a stable and mild liquid pool with more melt glass can be achieved to weld glasses with large gap. The maximum gap distance between two glasses is almost 40 µm which is an order of magnitude higher than other methods, and the joint strength of the glass weld with the natural contact gap of 10 µm is up to 64 MPa. In addition, an equivalent mathematical model about input energy of ultrashort laser was also given out. According to the model and the release of heat pressure, a detailed analysis about the relationship between the welding path length and joint strength has been made, and the experimental results are in good agreement with the theoretical analysis. At last, the encapsulation experiment of the welding glass with a closed area was carried out to prove that the sample can guarantee good sealing in 100 hours.