[18p-N304-1~15] 3.7 Laser processing

△ [18p-N304-12] Suppression of Ablation for Titanium by Femtosecond Double-pulse Laser Irradiation with First-pulse Fluence Adjusted Lower than the Ablation Threshold

〇Yuki Furukawa^1,2, Shunsuke Inoue^1,2, Masaki Hashida^1,2, Shuji Sakabe^1,2 (1.ICR, Kyoto Univ., 2.GSS, Kyoto Univ.)

Keywords:metal, ablation, fluence

Laser ablation of metals has been actively studied with increasing interest in its application to laser micro-fabrication. We have focused on the ablation by double-pulse femtosecond laser with the fluence near ablation threshold and have reported ablation depth of laser-produced crater with the time delay between the first and second pulses around 100 ps is smaller than that for single-pulse irradiation. This suggests that the pre-irradiation of the low-fluence first pulse would change the optical properties of titanium surface and suppress the ablation by the second pulse. In this work, to understand the mechanism of ablation suppression, we have investigated the dependences of ablation rate on the laser fluence and the time delay in detail. Suppression of ablation was observed for the first-pulse flucene of 0.4 ablation threshold. We discussed the contribution of the first-pulse irradiation to the suppression of ablation.