Novel fusion welding technology of glass using ultrashort pulse lasers

We have developed a novel fusion welding technology of glass using ultrashort laser pulses of fs~ps durations without preheating and absorbent, enabling selective melting of only the interface of glass plates. The present article overviews the welding technology of glass based on recent papers published by the authors along with our recent results, where a comprehensive study has been conducted on fusion welding of fused silica and borosilicate glass using ultrashort laser pulses at different pulse energies, pulse durations and repetition rates, numerical apertures of focusing lens and translation speeds of glass sample. Nonlinear absorptivity and mechanism for preventing cracks are also discussed. A thermal conduction model has been developed to calculated the transient temperature distribution and isothermal line of molten zone, and the calculated isothermal line agreed well with the experimental size and shape of the molten zone. Mechanical strength of fusion zone was as high as that of base material. Successful overlapped welding of 10 paths is demonstrated. High throughput has been realized, indicating that ultrashort pulse lasers are excellent heat source for fusion welding of glass.