Plasma evolution during metal ablation with ultrashort laser pulses

Area of Science:

• Physics
• Materials Science
• Laser Technology

Background:

• Ultrashort laser pulses enable precise material processing.
• Understanding plasma dynamics is crucial for optimizing laser-material interactions.

Purpose of the Study:

• To characterize plasma evolution during metal ablation using ultrashort laser pulses.
• To correlate plasma behavior with laser pulse duration and energy.
• To provide data for enhancing laser material processing efficiency.

Main Methods:

• Time-resolved transmission measurements from 200 fs to 3.3 ps.
• Plasma plume imaging using a gated intensified charge-coupled device (ICCD) camera.
• Analysis of plasma expansion velocity and attenuation dynamics.

Main Results:

• Two distinct plasma transmission minima were observed at different timescales.
• Initial attenuation (nanoseconds) attributed to electrons and sublimated mass.
• Later attenuation (150 ns) linked to thermal boiling (normal or explosive/phase explosion).

Conclusions:

• Plasma evolution dynamics significantly impact ultrashort laser pulse material processing.
• Understanding these dynamics allows for the estimation of optimal pulse repetition rates.
• Findings are valuable for scaling laser material processing speeds in the J/cm^2 fluence regime.