Ablation mechanism investigation and ablation threshold prediction of single crystal diamond irradiated by femtosecond laser

Femtosecond laser has proved to be a promising approach for single crystal diamond (SCD) processing, but the interaction mechanism between femtosecond laser and SCD is not well understood and need further theoretical investigation. In this paper, the simple rate equation was utilized to analyze the free electron excitation and evolution process and the temporal evolution of free electron density was simulated. In order to reveal the thermal interaction between electron and lattice subsystem of ablated SCD, the improved two temperature model which takes the variation of optical properties of the SCD surface caused by the excited plasma into account has been built up. The laser ablation threshold of SCD was also predicted under two theoretical models respectively. According to the single pulse ablation experiments, the simulated ablation thresholds of SCD are basically in agreement with the experimental results.