Processing of metals by double pulses with short laser pulses

Abstract

Experimental results related to the influence of time delayed pulses for ablation efficiency with short multi pulses (pulse duration of 5 ps) are reported. A significant improvement of the micro structuring quality at relatively high fluence regime in metals is obtained. Less removed or recast matter is observed and the processed surface appears to be smoother with better roughness. Ablation depths and burr heights are compared for single pulses and double pulses in steel, Al and Cu as a function of scans number. Best results are obtained for weak time delays, typically less than 1 ps

Femtosecond laser ablation of silver foil with single and double pulses

“…In addition, we have used double pulses with separations of up to 3.4 ns in a pump probe experiment to study a transition region between two logarithmic fluence regimes. Fairly extensive experimental results have been reported on ''single pulse'' femtosecond metal ablation, though few specifically on silver [3,7] but results on dual (or multiple) pulse ablation have been rather more limited [18][19][20][21][22][23][24][25][26][27][28][29][30][31]. By dual pulse it is always understood that the pulse separation is much less than the interpulse period (typically 1 ms) of the train of amplified femtosecond pulses used for ablation.…”

“…One objective of having dual or multiple pulses with small separations (<10 ps) can be to reduce the peak laser intensity in order to avoid air breakdown for a given total pulse energy [6]. Double pulses have also been used to try and improve the quality of laser materials processing [18][19][20].…”

Experimental study on double-pulse laser ablation of steel upon multiple parallel-polarized ultrashort-pulse irradiations

“…So, on the one hand, enhanced ablation was reported for different kinds of material when processing in double-pulse regime, compared to single-pulse processing with similar energies. This was determined, for example, in silicon [22], silver foils [25], aluminum and copper [27] and copper films [28][29][30], steel [27,31], or nickel in vacuum [16]. On the other hand, by contrast, a few studies identified insignificant or no increase of metal ablation for double-pulse processing, as stated for aluminum [32], copper [19], and titanium [21].…”

Ultrafast thermalization characteristics in Au film irradiated by temporally shaped femtosecond laser pulses

“…More recently, it is found that temporally shaped pulses train excitation enables new opportunities for optimal processing of materials [12]. A more precise manufacturing process can be achieved with such pulse train irradiation as observed by many groups in different materials [13][14][15]. For femtosecond laser ablation of metals, the diverse temperature relaxation mechanisms including the two temperature relaxation and thermal diffusion relaxation can be found to be responsible for the target thermalization in different timescales [16], whereas, it is believed that the two temperature relaxation, also called electron-phonon coupling relaxation mechanism plays an important role in the target thermalization process in high fluence regime [17].…”