Temporal-spatial measurement for electron-excitons collision coefficient in temporally shaped femtosecond laser-induced plasma

Temporally shaped femtosecond laser is a powerful tool for precision fabrication, especially for processing quality improvement and increasing manufacturing efficiency. In double-pulse femtosecond laser processing, self-trapped excitons (STEs) play a critical role in electron dynamics, material property transformation, and the formation of micro-nano structures. However, the mechanisms governing the collision between free electrons and excitons during plasma generation remain unclear, which hinders the development of theoretical models for shaped femtosecond laser processing. This study investigates the temporal-spatial electron dynamics in fused silica under temporally shaped femtosecond laser processing and improves the accuracy of the model for predicting the ablation structure morphology. Using pump-probe technology, the electron-exciton collision coefficient in laser-induced plasma is measured. Based on experimental results, an improved theoretical model for double-pulse femtosecond processing is proposed, and the predicted sectional profiles show good agreement with experimental data. These results deepen the understanding of the interaction mechanisms between temporally shaped femtosecond lasers and dielectric materials and advances the development of more accurate theoretical models, which offer critical insights for optimizing experimental designs and parameter optimization in temporally shaped femtosecond laser processing.