Fig. 1. Bidirectional-pumped fiber laser oscillator^[34]. (a) Structure schematic; (b) experimental results

Fig. 2. Fiber laser oscillator in spatial configuration developed by University of Southampton^[35]. (a) Structure schematic; (b) experimental results

Fig. 3. Tapered ytterbium-doped fiber laser oscillator in spatial configuration^[37]. (a) Structure schematic; (b) output laser beam profile

Fig. 4. 3 kW fiber laser oscillator developed by Coherent Inc.^[42]. (a) Structure schematic; (b) experimental results

Fig. 5. Schematic of 10 kW extreme large mode area fiber laser oscillator in spatial configuration developed by Laserline Inc.^[52]. (a) Single-end pump; (b) dual-end pump

Fig. 6. 2 kW all-fiber laser oscillator developed by Rofin^[40]. (a) Structure schematic; (b) output power curve

Fig. 7. 5 kW all-fiber laser oscillator in Fujikura Inc.^[49]. (a) Structure schematic; (b) output power; (c) spectra

Fig. 8. 5 kW all-fiber laser oscillator in NUDT^[48]. (a) Structure schematic; (b) output spectra

Fig. 9. 5 kW-level all-fiber laser oscillator in University of Jena^[67]. (a) Structure schematic; (b) output spectra

Fig. 10. 8 kW all-fiber laser oscillator in Fujikura Inc.^[53]. (a) Structure schematic; (b) output spectra

Fig. 11. 8 kW monolithic fiber laser oscillator in NUDT^[54]. (a) Structure schematic; (b) output spectrum and beam profile

Fig. 12. Schematic of 5 kW all-fiber laser amplifier and GT-wave fiber in CAEP^[97]. (a) Amplifier structure; (b) GT-wave fiber

Fig. 13. 5 kW all-fiber laser amplifier in Tianjin University^[99]. (a) Structure schematic; (b) laser beam quality

Fig. 14. 6 kW all-fiber laser amplifier in Tsinghua University^[106]. (a) Structure schematic; (b) laser beam quality

Fig. 15. 6 kW all-fiber laser amplifier in NUDT^[126]. (a) Structure schematic; (b) laser beam quality

Fig. 16. 13 kW all-fiber laser amplifier in NUDT^[126]. (a) Structure schematic; (b) laser beam quality

Fig. 17. Output power and spectra of 5 kW all-fiber laser amplifier in CAEP^[110]. (a) Output power; (b) output spectra

Fig. 18. 5 kW narrow linewidth all-fiber laser amplifier in CAEP^[33]. (a) Structure schematic; (b) mechanical structure of YDF winding;(c) output laser spectra; (d) beam quality

Fig. 19. 6 kW all-fiber laser amplifier in NUDT^[107]. (a) Structure schematic; (b) output spectrum; (c) laser beam quality

Fig. 20. 6 kW narrow linewidth all-fiber laser amplifier in NUDT^[114]. (a) Structure schematic; (b) output spectra; (c) beam quality

Fig. 21. 5 kW narrow linewidth all-fiber laser amplifier in NUDT^[127]. (a) Structure schematic; (b) output power and laser beam quality; (c) output spectra

Fig. 22. 4.3 kW broadband fiber laser in University of Jena^[98]. (a) Structure schematic; (b) output spectra; (c) laser beam quality

Fig. 23. 5 kW single-mode fiber laser amplifier in OFS Lab.^[129]. (a) Structure schematic; (b) output power; (c) output spectra

Fig. 24. Schematic of oscillating-amplifying integrated fiber laser^[140]

Fig. 25. Schematics of oscillating-amplifying integrated fiber laser in co-pumped and bi-pumped configurations^[141]. (a) Co-pump;(b) bi-pump

Fig. 26. 5 kW-level oscillating-amplifying integrated fiber laser in NUDT^[145]. (a) Structure schematic; (b) laser beam quality

Fig. 27. Schematic of 22 kW-level oscillating-amplifying integrated fiber laser^[150]