Hybrid laser system with blue laser and near-infrared fiber laser for copper welding

Copper is widely used in many industries due to its high electrical conductivity, and copper welding is significant technology. High power near-infrared fiber lasers have been used in laser material processing in many fields since they provide high electric-optic conversion efficiency and excellent laser beam quality. However, copper welding with nearinfrared fiber lasers is challenging. Absorption of copper is low for near-infrared radiation, and copper diffuses heat rapidly at welding spots due to its high thermal conductivity. Previously we reported a hybrid laser system with a 150-W blue laser and a 1-kW near-infrared fiber laser for copper welding. Blue laser irradiation generates stable molten pool at welding spots due to high absorption of copper at the wavelength, and it assists near-infrared fiber laser to generate stable and spatter-less welding during the process. In this paper, we present a hybrid laser system with a 1-kW blue laser and a 3-kW near-infrared laser. The blue laser consists of blue laser diode modules with 250-W optical output power from optical fiber with 110-m core diameter. The laser diode modules contain blue laser diode chips in side lead packages, and the optical output power from the package is 13.2 W at 8.5-A rated current. We have also demonstrated laser processing to pure copper with the hybrid laser system. Uniform beads and approximately 2 mm penetration depth has been generated.