Micromachining of copper by femtosecond laser pulses

▸ We have reported new experimental and theoretical results on the femtosecond laser ablation for copper at fluences up to 408J/cm2. ▸ The present model simulations correlate well with the experimental data over a broad range of laser fluences from 0.8 to 400J/cm2. ▸ The good correlation suggests that the proposed model is an efficient and accurate tool for predicting ultrafast laser material ablation. Simulation results of femtosecond laser ablation of copper were compared to experimental data. The numerical analysis was performed using a predictive model, including a two temperature model, an optical critical point model with three Lorentzian terms, two phase change models for melting and evaporation under superheating, and a phase explosion criterion for ejection of metastable liquid decomposing into droplets and vapor phase. The experiments were conducted with a 120-fs, 800-nm Ti:sapphire lasers for fluences up to 408J/cm2. The ablation depths were measured, and the ablation rate was estimated. It was shown that the present numerical simulations correlate well with the experimental data over the entire range of the laser fluences investigated except for those below 0.8J/cm2, indicating that the proposed model is an accurate and efficient tool for predicting ultrashort-pulsed laser material ablation.