Abstract
The drilling of copper using a dual-pulse femtosecond laser with wavelength of 800 nm, pulse duration of 120 fs and a variable pulse separation time (0.1–150 ps) is investigated theoretically. A one-dimensional two-temperature model with temperature-dependent material properties is considered, including dynamic optical properties and the thermal-physical properties. Rapid phase change and phase explosion models are incorporated to simulate the material ablation process. Numerical results show that under the same total laser fluence of 4 J/cm2, a dual-pulse femtosecond laser with a pulse separation time of 30–150 ps can increase the ablation depth, compared to the single pulse. The optimum pulse separation time is 85 ps. It is also demonstrated that a dual pulse with a suitable pulse separation time for different laser fluences can enhance the ablation rate by about 1.6 times.
Highlights
Ultrashort lasers have been successfully demonstrated in drilling, cutting, surface structural modification and internal modification of transparent material because of their minimal heat-affected zone [1] and high peak power intensity [2]
This paper reports the numerical results of thermal ablation of copper foil by a single- and dual-pulse femtosecond laser for laser fluences of 3–8 J/cm2
It is found that a dual pulse with a total laser fluence of 4 J/cm2 and a pulse separation time around 85 ps can increase the amount of material ablated, as compared to a single pulse
Summary
Ultrashort (pico- or femto-second) lasers have been successfully demonstrated in drilling, cutting, surface structural modification and internal modification of transparent material because of their minimal heat-affected zone [1] and high peak power intensity [2]. Experiments with single- or multi-shot ablation or the drilling of metal under different laser parameters have been presented, e.g., laser fluence [7,8,9] and pulse duration [10,11,12]. Numerous experiments on the enhancement of metal drilling using a dual-pulse nanosecond laser have been presented [15,16,17]. The numerical results of the thermal response and andablation the ablation generated bydual-pulse the dual-pulse femtosecond laser under different separation the depthdepth generated by the femtosecond laser under different separation times times and laser fluences are presented and discussed .
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