Abstract

We demonstrate highly efficient ablation of silicon by use of BiBurst mode, which is composed of GHz bursts in MHz bursts. Ablation by the conventional irradiation scheme of femtosecond laser pulses (single-mode) generates detrimental damage on the ablated surface due to air ionization at the intensity above a critical value. In contrast, the BiBurst mode ablation can prevent the air ionization at the input power equal to or even higher than the single-mode due to lower intra-pulse intensities. Thus, BiBurst mode can achieve 23 times ablation speed without degrading the ablation quality compared to that by the single-mode ablation under the conditions that avoid the air ionization.

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