High power blue laser and copper welding with near-infrared fiber laser

Copper is widely used in many industries due to high electrical conductivity and with the recent acceleration of EV shift, the needs for copper material processing are rapidly increasing. High power near-infrared (NIR) fiber lasers have been used in laser processing since high electric-optic conversion efficiency and excellent laser beam quality. However, copper welding with NIR fiber lasers is challenging. The absorption of copper is low in the NIR, and copper with high thermal conductivity diffuses the heat rapidly at welding spots. Previously we reported the hybrid laser system with 1- kW blue laser and 3-kW NIR fiber laser for copper welding. Blue laser with high absorption of copper generates stable molten pool at welding spots and assists NIR fiber laser processing for uniform welding and less spattering. In this paper, we present the improvements of blue laser. The first one is high power 2-kW with 300-μm core diameter and the second one is high brightness 1-kW with 200-μm. These are achieved by high power laser diode module, which has 500-W output power with 110-μm core diameter, and fiber-bundled beam combiner. Copper welding characteristics using this improved blue laser and NIR fiber laser would also be discussed.