Fig. 1. Schematic of 2 kW fiber laser structure with 14 μm core diameter

Fig. 2. Output spectrogram

Fig. 3. Output beam quality graph

Fig. 4. Variation of fusion width and depth with output power during laser welding

Fig. 5. Comparison of weld effects of three lasers on copper overlap welding. (a) 50 μm core diameter; (b) 20 μm core diameter; (c) 14 μm core diameter

Fig. 6. Variation of fusion width with defocus amount during laser welding