Fig. 1. Schematic of GTWave fiber structure^[37]. (a) Cross section; (b) side-view

Fig. 2. Schematic of solid laser coupled by evanescent field^[19]

Fig. 3. GTWave fiber^[24]. (a) Drawing principle of GTWave fiber; (b) multiple arrangements of fiber structure (120 denotes the signal fiber, 121 denotes the pump fiber)

Fig. 4. Hundred watt GTWave fiber laser^[18]. (a) Output power curve; (b) product photo

Fig. 5. 200 W GTWave fiber laser developed by SPI^[25]. (a) Output power curve; (b) beam quality

Fig. 6. Schematic of 400 W fiber amplifier developed by SPI^[27]

Fig. 7. 1 kW GTWave fiber laser^[29]. (a) Schematic diagram; (b) output power; (c) spectrum diagram

Fig. 8. Output spectra of 2 kW fiber laser developed by SPI^[30]

Fig. 9. Schematic of 2 kW fiber laser structure developed by IPG^[31]

Fig. 10. Schematic of fiber laser in IPG’s patent^[33-34]

Fig. 11. Schematic of 10 kW fiber laser structure developed by IPG^[35]

Fig. 12. Schematic of cascade-amplified 1 kW GTWave fiber laser structure^[40]

Fig. 13. Schematic of 2 kW cascaded amplified fiber oscillator^[41-42]

Fig. 14. Schematic of 4 kW cascaded amplified fiber oscillator^[46]

Fig. 15. Schematic of (2+1) GTWave fiber laser structure^[48]

Fig. 16. Schematic of (3+1) GTWave fiber structure^[49]. (a) Cross section; (b) side-view

Fig. 17. Schematic of (8+1) GTWave fiber amplifier structure^[51]

Fig. 18. Schematic of (8+1) GTWave structure^[51]. (a) Cross section graph; (b) side-view

Fig. 19. Schematic of two stages pump 100 W GTWave fiber oscillator^[53]