Improved prediction of ultrashort pulse laser ablation efficiency

Abstract

Achieving maximum efficiency and precision in ultrafast laser ablation is crucial for micromachining applications, where advanced models are pivotal to predict and optimize laser-material interactions. Existing models for predicting laser ablation efficiency assume an equivalence between the threshold fluence determined by ablation depth and diameter. However, experimental measurements have shown this assumption does not hold. In this work, we present a new model for ablation efficiency by introducing a minimum ablation depth (d0) into the ablation depth equation, which accounts for the discrepancy between depth and diameter thresholds. We have designated this framework as the threshold-refined ablation model (TRM). Unlike the Furmanski model, which places the fluence corresponding to maximum ablation efficiency at e2 times the threshold fluence, the TRM predicts this maximum occurs at a lower range (three to five times the threshold fluence), aligning with experimental findings. The new model has been validated against single-pulse experiments for metals, glasses, and dielectrics. For most cases, the TRM demonstrates significantly better agreement with experiments, providing enhanced predictive accuracy for sub-ps and fs pulses.