Fig. 1. Fiber cross section and its refractive index profile^[26]

Fig. 2. 976-nm tapered fiber laser^[26]

Fig. 3. Refractive index profile of W-profile fiber^[27]

Fig. 4. 977-nm W-profile Yb-doped fiber laser^[27]

Fig. 5. Refractive index profile of saddle-shaped fiber^[28]

Fig. 6. 976-nm saddle-shaped Yb-doped fiber laser^[28]

Fig. 7. 978-nm all-solid photonic bandgap fiber laser and its fiber cross section^[32]

Fig. 8. 978-nm Yb-doped fiber laser with 151-W output power^[33]

Fig. 9. 976-nm Yb-doped phosphate double-clad fiber amplifier and its fiber cross section^[34]

Fig. 10. Refractive index profile of fiber with core/cladding diameter of 95/125μm^[35]

Fig. 11. 976-nm Yb-doped phosphate fiber laser amplification system^[35]

Fig. 12. Master oscillator power amplifier with 39-W output power and its fiber cross section^[36]

Fig. 13. 980-nm photonic crystal fiber amplifier and its frequency doubling system^[37]

Fig. 14. 977-nm fiber laser with 1.73-W output power^[39]

Fig. 15. 980-nm fiber amplifier with 2.65-W output power^[40]

Fig. 16. 980-nm fiber amplifier with 6.8-W output power^[41]

Fig. 17. 981.7-nm Yb-doped fiber laser with 16.7-Woutput power^[42]

Fig. 18. 100-W-level all-fiber main oscillator power amplifier^[43]