Enhancement of femtosecond laser-induced surface ablation via temporal overlapping double-pulse irradiation

Abstract

This paper reports the physical phenomenon of the temporal overlapping double femtosecond laser-induced ablation enhancement at different time delays. Detailed thermodynamic modeling demonstrates the ablation enhancement is highly dependent on the first pulse’s laser fluence. In the case of the first pulse laser fluence being higher than material’s ablation threshold, the ablation enhancement is attributed to optical absorption modification by the first pulse ablation. While the first pulse’s laser fluence is lower than the material’s ablation threshold, the first pulse-induced melting leads to much higher absorption of the second pulse. However, for the case of the first pulse’s laser fluence even lower than melting threshold, the ablation enhancement decreases obviously with time delay. The results of the temporal overlapping double femtosecond laser ablation of poly( ε -caprolactone) are in good agreement with the theoretical predictions.