Processing results on the surfaces of aluminum sheets using picosecond laser beams delivered over free space, 3-m-long AR-HCF1 and 3-m-long AR-HCF2

The experiment results show that the AR-HCF sample with a d/D value of ~0.68 exhibits high optical mode purity, which is critical for overcoming the laser beam instability due to fiber micro-bending. Single-shot and in-line processing procedures of aluminum sheets were performed in our experiments, verifying that the ultrafast laser beam delivered through 3-m-long AR-HCF sample can be used to achieve similar manufacturing quality with that delivered over free space.