Fig. 1. Schematic diagram of the experimental setup for the spatial double-pulse laser ablation.

Fig. 2. SEM images, 3D reconstructions and 2D profiles of craters created by the splitted double-pulse laser beams at different gaps of (a) 100 μm, (b) 80 μm, (c) 60 μm, (d) 0 μm, and (e) by single laser beam at a total laser power of 10 W.

Fig. 3. SEM images of (a) two intersecting grooves processed by double laser pulses and (b) zoom-in state.

Fig. 4. The schematic diagram of distributions of energy field (upper), temperature field (middle) and the interaction between laser and silicon (bottom) at different gaps.(a) Large gap. (b) Optimal gap. (c) Zero gap.