We report on micromilling cavities into fused silica by a 1030 nm femtosecond laser using 2.17 GHz bursts. The milled cavities show an increased depth per layer for a higher number of pulses per burst while the ablation efficiency is also increased. The maximum ablation efficiency for the optimum fluence achieved in our experiments is $3.05\;{{\rm mm}^3}/{\rm min}/{\rm W}$ for a burst number of 10, which is 7.4 times higher than for the non-burst condition ($0.41\;{{\rm mm}^3}/{\rm min}/{\rm W}$). Furthermore, the ablation threshold for each sub-pulse is significantly reduced from $0.64 \; {\rm J}/{{\rm cm}^2}$ for the non-burst condition to $0.15\; {\rm J}/{{\rm cm}^2}$ for 10 bursts. Beside the ablation efficiency, the surface roughness is also increased with the increasing burst number, while two ablation behaviors can be distinguished, namely, a gentle ablation regime for lower burst numbers and a coarse ablation regime, dominated by breaking out the surface rather than ablating it.

中文翻译：

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在微加工熔融石英中使用GHz猝发提高了烧蚀效率

我们报告了使用2.17 GHz突发脉冲的1030 nm飞秒激光将腔磨成熔融石英的过程。铣削的型腔显示出每层的深度增加，每个突发脉冲数更多，同时消融效率也提高了。在我们的实验中，达到最佳通量的最大烧蚀效率为$ 3.05 \; {{\ rm mm} ^ 3} / {\ rm min} / {\ rm W} $，突发数量为10，是7.4倍比非爆破条件（$ 0.41 \; {{\ rm mm} ^ 3} / {\ rm min} / {\ rm W} $）大。此外，每个子脉冲的消融阈值从$ 0.64显着降低。{\ rm J} / {{\ rm cm} ^ 2} $（非爆破条件）为$ 0.15 \; {\ rm J} / {{\ rm cm} ^ 2} $连续10次。除了烧蚀效率外，表面粗糙度还随爆破次数的增加而增加，同时可以区分两种烧蚀行为，即，较低爆破次数的温和烧蚀方式和以打孔而不是烧蚀为主的粗略烧蚀方式它。