Modeling highly efficient femtosecond laser ablation of aluminum for cutting.

This article presents high-efficiency ablation of aluminum using femtosecond laser processing with a pulse duration of 300 fs and a laser wavelength of 1035 nm. A series of stationary irradiation experiments were conducted at repetition rates f = 50 kHz, 100 kHz, 200 kHz, 500 kHz, and 1 MHz. The comparison results indicated that as the repetition rate increased above a laser fluence F ≈ 1 J/cm, the ablation rate ΔL decreased. This phenomenon could be attributed to particle shielding, which occurs as the density of particles increases with increasing the volume of ablated targets, corresponding to an increase in F. The volume ablation rate ΔV was obtained in 0.53 ≤ F ≤ 2.59 J/cm at f = 100 kHz, revealing that ΔV at F = 2.59 J/cm was ~ 3.4 times higher than that at F = 1 J/cm. Multibeam laser processing, utilizing a diffractive optical element, was employed to reduce f, thereby suppressing particle shielding while preserving the total laser fluence and scan speed. The experimental groove shapes were accurately estimated using a developed analytical model. These findings provide valuable insights for achieving high-efficiency laser cutting of aluminum in the realm of secondary battery manufacturing.