Femtosecond Laser Ablation Modeling of Tilted Microfeatures on Copper Surfaces

Femtosecond (fs) laser ablation produces precise microfeatures due to the laser-material interaction at timescales shorter than the electron-phonon coupling. In order to eliminate the extensive trial-and-error experimentation needed for for process optimization, modeling of fs laser ablation is often required. A pulse-based Two-Temperature Model (TTM) was developed in our previous work to predict the ablated groove geometry, and validated for low-corrosion tool steel. However, due to the complex laser-material interaction involved, it is necessary to validate the model for different materials, processing strategies and surface structures. This paper presents a comprehensive study on the prediction of fs laser-ablated inclined grooves on copper surfaces using the pulse-based TTM. In this work, the effect of inclination angle and process parameters such as scanning speed and laser fluence on the groove geometry were evaluated through simulation and experiments. The fabricated tilted grooves on copper surfaces were characterized using a cross-sectional optical microscopic analysis. The effectiveness of the calibrated TTM for predicting the geometry of the tilted grooves has been analysed. This paper underlines the potential of fs laser ablation for the manufacturing of highly precise tilted microfeatures and the suitability of the calibrated TTM for an accurate prediction of feature geometries.