Laser Welding of High Reflective Metals using Blue, Green, and Hybrid Beams: A Review

Colored and colored-infrared (IR) hybrid laser technologies have recently gained attention as promising alternatives to conventional IR sources for welding highly reflective metals such as aluminum and copper. These emerging technologies are particularly relevant to electric-vehicle battery manufacturing, power-electronic packaging, and high-precision joining of conductive materials, where conventional IR lasers often face absorption and stability limitations. This review summarizes developments in blue (450 nm), green (515-532 nm), and colored-IR hybrid systems, focusing on their welding characteristics and absorption behavior. Blue and green lasers exhibit improved energy coupling, enabling deeper penetration and wider bead formation at reduced power levels, whereas IR lasers often suffer from unstable keyhole behavior and spatter formation that degrade weld quality. Hybrid systems have shown additional benefits in stabilizing keyhole formation by preheating the surface with visible light and maintaining deep penetration with IR radiation. Influence of differences in energy density, beam size, emission mode (pulsed vs. continuous wave), and experimental setup were also discussed in relation to their impact on welding behavior, aiming to clarify why colored lasers exhibit superior performance over IR lasers for highly reflective materials. Although existing studies remain limited in providing quantitative comparisons, this review was intended to enhance understanding of the underlying mechanisms and to offer insights for optimizing future laser welding processes.