Evaluation of Molten Zone in Micro-welding of Glass by Picosecond Pulsed Laser

Glass materials have been widely used in optics, MEMS, electronics and biomedical applications because of their excellent optical, mechanical and chemical properties. Fusion welding by ultrashort pulsed laser has been proposed as a promising technique for glass joining, since joining can be accomplished without an intermediate layer and mechanical contact. However, to apply a fusion welding technique by ultrashort pulsed laser as a reliable joining method, it is important to understand the mechanical properties of the weld seam since glass materials are very sensitive to temperature gradients. Therefore, a method of evaluating the weld seam in the fusion welding of glass by picosecond pulsed laser was discussed, and its mechanical strength was investigated. A larger optical contact area had a great influence on the shear load of the weld seam, while a smaller optical contact area could reduce the influence of the contact area on the measurement of shear load. Therefore, it was important to reduce the optical contact area to accurately evaluate the shearing strength of weld seam. The mechanical strength of the weld seam reduced at a low pulse repetition rate. High bending strength and shear stress could be obtained at a proper pulse repetition rate.