High-quality laser processing of fused silica with bursts of ultrafast pulses

A material processing method is proposed to cut and drill micro-holes of different shapes on fused silica by the burst mode of ultrafast laser. The processing mechanism between ultrafast laser and fused silica is analyzed by ablation experiments. The ablation diameter and the heat-affected zone (HAZ) at the burst mode I decreases significantly compared with the non-burst mode, which is beneficial to improving the quality of laser cutting and drilling due to the reduction of the thermal load. Besides, the ablation rate on fused silica reaches the maximum at two pulses per burst because of the effect of heat accumulation and redeposited thermal particles. To realize high-quality laser processing on fused silica, the effecting factors, including different burst modes and the number of sub-pulses, on the groove's geometry and morphology are also investigated. The results show that the edge collapse of the groove can be reduced using burst mode I. Laser cutting with low cross-section surface roughness and high edge quality on fused silica is achieved, and the slight edge collapse and low taper high-quality micro-holes are obtained.