Single-shot ablation threshold of chromium using UV femtosecond laser pulses

摘要

Single-shot ablation threshold for thin chromium film was studied using 266 nm, femtosecond laser pulses. Chromium is a useful material in the nanotech-nology industry and information on ablation threshold using UV femtosecond pulses would help in precise mi-cromachining of the material. The ablation threshold was determined by measuring the ablation crater diameters as a function of incident laser pulse energy. Absorption of 266 nm light on the chromium film was also measured under our experimental conditions, and the absorbed energy single-shot ablation threshold fluence was 46 ± 5 mJ/cm~2. The experimental ablation threshold fluence value was compared to time-dependent heat flow calculations based on the two temperature model for ultrafast laser pulses. The model predicts a value of 31.6 mJ/cm~2 which is qualitatively consistent with the experimentally obtained value, given the simplicity of the model.