Nonlinear and saturable absorption influence on laser ablation threshold of copper in z-scan experiments

In this work, a new model of laser ablation threshold of copper is presented. Nonlinear and saturable absorption in copper oxide layer on semi-bulk copper was taken into account for prediction of ablation threshold change with varying peak intensities in z-scan type experiment for the first time. Normalized transmission equation of copper oxide layer including nonlinear and saturable absorptions in z-scan was incorporated in ablation threshold model. The new model has a good agreement with experimental results of ablation threshold dependence on sample vertical z-scan position measured for copper using picosecond laser.