Ablation profile prediction of hard brittle fused silica optics irradiated by single-pulse femtosecond laser

Fused silica optics are extensively utilized in high-power laser facilities due to their superior optical characteristics. Femtose cond laser direct writing is one of the most precision processing techniques that has been used to create functional microstructures on the surfaces of fused silica optics. Complex physical processes occur when femtosecond laser ablates fused silica materials, therefore, precision control of the ablation structure profile during the interaction between femtosecond lasers and fused silica remains a significant challenge. This study addressed this challenge by employing finite element modeling to simulate and analyze the evolution of the ablation profile. Simulations of single-pulse femtosecond laser irradiation were conducted to investigate the impact of laser parameters on the ablation profile. In the model, the evolution of electrons temperature and lattices temperature were revealed according to the two-temperature equation. The ablation temperature isotherm was used to predict the femtosecond laser ablation profile curve. The accuracy of the prediction model was evaluated by comparing the predicted contour curves of various single pulse energies with the experimental results. The finding indicates that the ablation profiles generated by single-pulse femtosecond laser closely match theoretical predictions, with maximum discrepancies in diameter and depth are only 14.36% and 11.07%, and the average deviations of diameter and depth are 6.73% and 7.28%, which verifies the accuracy of the model. With the evolution of single pulse energy, the ablation morphology will appear obvious inner and outer regions and sub-wavelength laser-induced periodic surface structures (LIPSS). The accurate prediction of femtosecond laser ablation profiles is a significant advancement, paving the way for more precise control in laser processing applications.