Surface damage induced by a combined millisecond and nanosecond laser

Area of Science:

• Materials Science
• Laser Physics
• Surface Engineering

Background:

• Investigating laser-induced surface damage is crucial for material processing.
• Understanding the synergistic effects of multiple laser pulses is an active research area.

Purpose of the Study:

• To compare surface damage morphologies on single-crystal silicon induced by combined pulse lasers (CPL) and single millisecond (ms) lasers.
• To elucidate the underlying mechanisms responsible for observed differences in surface damage.

Main Methods:

• Experimental investigation using optical microscopy to inspect surface damage.
• Development of a two-dimensional spatial axisymmetric model to simulate laser-material interactions.
• Comparative analysis of damage under CPL (ms + ns lasers) and single ms laser irradiation at equivalent energy densities.

Main Results:

• CPL irradiation resulted in more severe surface damage compared to single ms laser irradiation.
• Distinct damage features, including surface cleavage, ablation, and fold areas, were observed under CPL.
• The ms laser component of CPL induced a preheating effect, enhancing subsequent damage by the ns laser component.

Conclusions:

• The combined effect of preheating by the ms laser and direct surface damage by the ns laser explains the enhanced damage observed with CPL.
• CPL induces complex surface morphologies not seen with single ms laser irradiation.
• This study provides insights into laser-matter interactions for optimizing laser-based material modification processes.