Fusion Welding of Glass Using Femtosecond Laser Pulses with High-repetition Rates

into borosili-cate glass (Schott D263) at different pulse energies, repetition rates and traveling velocities for local melting. The temperature distribution was calculated using a thermal conduction model where instan-taneous heat is periodically deposited in a moving rectangular solid. The nonlinear absorptivity of the femtosecond laser pulses increased significantly as the repetition rate increased by the contribution of avalanche ionization caused by the increase in temperature at the laser-irradiation region. The calcu-lated values agreed well with the experimental melt dimensions in a velocity range of