Femtosecond laser-induced ablation and the ultrafast dynamics of MgO(111) surfaces

Single-shot laser damage of polished MgO (111) surfaces induced by 800 nm pulses at different laser pulse duration was studied by scanning electron microscopy (SEM) and time-resolved measurements of reflectivity. SEM observations after laser irradiation indicated that substantial surface fracture dominated over rapid vaporization. The linear relationship between the ablation area and the logarithm of the pulse energy provided the single-shot ablation threshold. The pump-probe technique was used to investigate the change of the reflectivity during and after laser irradiation. The results showed that the charged particle emission time was about 15 ps. The ablation mechanism was also discussed.