ULTRAFAST LASER WITH HIGH ENERGY AND HIGH AVERAGE POWER FOR INDUSTRIAL MICROMACHINING: COMPARISON PS-FS

摘要

Ultrafast lasers present a growing interest for industrial applications such as surface structuring or thin film selective ablation. Indeed, they combine the unique capacity to process any type of material, such as dielectrics, semiconductors or metals, with an outstanding precision and a reduced affected zone. In this paper, we report on results about surface engraving of metals (Al, Cu, Mo, Ni), semiconductor (Si) and polymer (PC) using a picosecond thin disk Yb:YAG-amplifier, which could be used in the picosecond regime as well as in the femtosecond regime by simply changing the seed laser source. In the picosecond regime the oscillator pulses (34 ps) can be directly amplified which leads to a quite simple and efficient amplifier architecture. On the other hand, a broadband femtosecond oscillator and a CPA configuration can be used in order to obtain pulse duration down to 900 fs. The results obtained with this thin disk laser are compared to ones achieved with two commercial femtosecond lasers respectively based on Yb-doped crystals and fibers, and operating at similar output power levels (up to 15 Watt). Finally, we have considered etch rate and process efficiency for both ps- and fs-regimes as a function of average power, of fluence and of intensity.