In recent years, the use of all solid-state high power green lasers (more than 100 W) has spread into manufac-turing lines. Especially in liquid crystal display (LCD) industries, high power green lasers are becoming highly sought after for the annealing process of amorphous-silicon (a-Si), instead of conventional eximer lasers, due to lower maintenance costs, higher stability and better results in the crystallization process. Laserfront Technologies, Inc.(LFT) has developed a very stable all solid-state high power green laser using the intra cavity second harmonic generation (SHG) technique of the Nd: YAG laser. Its maximum output power has reached 259W, which is the highest power output using the intra cavity SHG technique currently known in the world. In this paper, we report its features and demonstrate cutting copper, which is well known as being a very difficult metal to cut with infrared lasers due to very high reflectivity.
