Study on mechanism of biburst mode in femtosecond laser ablation through in-situ monitoring

In this work, study on laser ablation efficiency was conducted through single-pulse, MHz and burst in burst (biburst) regime. High efficiency of 0.40 mm3min-1W−1 was reached using biburst under 40 W. In-situ monitoring device was used to capture visual images, which were then performed image processing to reveal the plasma shielding or molten splashing mechanism in laser ablation. High-speed camera was used to observe plasma and plume particles were analyzed to show that the increasing efficiency under biburst mode was caused by the enhanced molten splashing and molten materials spattering from the surface. This study provides a new approach for the investigation on material removal mechanisms induced by ultrafast laser.