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_rep = 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 F₀ ≈ 1 J/cm², 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 F₀. The volume ablation rate ΔV was obtained in 0.53 ≤ F₀ ≤ 2.59 J/cm² at f_rep = 100 kHz, revealing that ΔV at F₀ = 2.59 J/cm² was ~ 3.4 times higher than that at F₀ = 1 J/cm². Multibeam laser processing, utilizing a diffractive optical element, was employed to reduce f_rep, 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.