Ablation of metals by ultrashort laser pulses

Abstract

Ablation of Fe by ultrashort laser pulses with durations 0.1, 1, and 5 ps were investigated experimentally. The laser fluence varied from the ablation threshold up to 100 J cm−2. Above 1 J cm−2, the ablation rate depended on the laser pulse duration, with the shortest pulse producing the highest value. A change in the ablation rate as the laser fluence increased was also observed. These results were analysed using molecular dynamics simulations. We show that the change in the ablation rate is connected to an overheating of the material above the critical point, which results in a steep rise of the pressure developed. Furthermore, due to the electron heat diffusion, the overheated volume increases and involves material located deeper than the skin depth. An increase in the pulse duration results in a decrease in the degree of overheating.

Molecular Dynamics Simulations of Crater Formation Induced by Laser Ablation on the Surface of α-Fe Substrate

“…The energy of the photons was transformed into kinetic energy (in the irradiated atoms) within a characteristic time (τ eq ) [8]. Time τ eq corresponds to the relaxation time between electrons and the lattice, which typically takes between hundreds of femtoseconds to several tens of picoseconds for metals, depending on the properties of the target [1,10,11]. Here, we adopted a typical relaxation time of τ eq ~ 10 ps.…”

“…These changes are induced by a complex combination of processes, including the transmission of light energy, carrier dynamics, heating, and mechanical processes. As a result, the fundamental mechanisms underlying laser ablation have yet to be fully elucidated, which has hindered the further development of this technology for manufacturing [9][10][11][12]. In this study, we adopted molecular dynamics (MD) at the microscopic scale to explore structural metamorphoses induced by light, heat, and mechanical processes.…”

Synthesis of Magnetic Nanoparticles by Ultrashort Pulsed Laser Ablation of Iron in Different Liquids

“…[25] For higher fluences as econd term, taking into account ac hange of ablation depth at higherf luences due to ac hanged penetration depth, [26] needs to be introduced [Eq. [25] For higher fluences as econd term, taking into account ac hange of ablation depth at higherf luences due to ac hanged penetration depth, [26] needs to be introduced [Eq.…”

“…where A is ac onstant that takes into account the reflectivity, E 0 is the pulse energy and d is the penetration depth of the laser beam (18 nm). [25] For higher fluences as econd term, taking into account ac hange of ablation depth at higherf luences due to ac hanged penetration depth, [26] needs to be introduced [Eq.…”

Single-frame measurement of complex laser pulses tens of picoseconds long using pulse-front tilt in cross-correlation frequency-resolved optical gating

“…Other health-care applications from hair and tattoo removal [34][35][36] to cancer treatments to dental drilling [37][38][39] use ps pulses. And they find use in material processing applications from glass cutting [40] to circuit-board etching [41] to micromachining [42][43][44]. The accuracy and efficiency of all of these applications depend heavily on the ability to measure the laser pulses.…”