Ablation depth enhancement on a copper surface using a dual-color double-pulse femtosecond laser.

We investigate the femtosecond laser ablation of copper with a dual-color double-pulse femtosecond laser at the wavelengths of 515 nm and 1030 nm. By properly choosing the energy of the 515 nm pulse, the optical properties such as surface reflectivity and absorption coefficient on copper surface can be modified to increase the absorption of the subsequent 1030 nm pulse. The ablation depth of dual-color double-pulse laser is at least 50% higher than the total ablation depth of both the 515 nm and 1030 nm pulses, provided that the inter-pulse delay of the double-pulse laser is within the electron-phonon coupling time. The ablation depth enhancement on a copper surface using a dual-color double-pulse femtosecond laser is of significant interest for scientific research and industrial application.