[15a-512-1~12] 3.7 Laser processing

[15a-512-12] Control of glass welding phenomena induced by temporally modulated picosecond-pulse train

〇Akinao Nakamura¹, Masaaki Sakakura², Yasuhiko Shimotsuma¹, Kiyotaka Miura¹ (1.Kyoto Univ., 2.SACL, Kyoto Univ.)

Keywords:picosecond laser, micro-welding, temporal modulation

An ultrashort pulsed laser has been attracting much interest as a useful tool for micro-welding of transparent materials such as glass materials. Because local melting can be induced by nonlinear photoexcitation inside transparent materials using ultrashort pulsed laser, thermal damage that often occurs on the free surface of solids can be minimized. However, because laser pulses of large energy are necessary to induce local melting inside glasses, cracks are often generated by large fluctuation of light absorption and thermal stress. Generation of cracks is not desirable for welding, because they might reduce the joining strength and device strength.In this work, I tried to improve ultrashort pulsed laser welding to reduce crack generation with larger laser power. I supposed this improvement can be realized by applying temporal modulation of laser pulse energies by an arbitrary-waveform-pulse-generator. To confirm the hypothesis, I irradiated ps laser pulses with temporal energy modulation onto some kinds of glass and observed them. In addition, assuming that the size of molten areas is related to breaking strength, I measured them after irradiation with and without temporal energy modulation, and considered the effect of modulation.