Fig. 1. Peak powers of various kinds of ultrafast fiber lasers^[4⁃23]

Fig. 2. Operation principle of Mamyshev generator^[4]

Fig. 3. Typical setup of oscillator based on two cascaded Mamyshev generators^[4]

Fig. 4. First all-fiber Mamyshev oscillator demonstrated by researches of IPG company^[22]

Fig. 5. Experimental setup of polarization maintaining Mamyshev oscillator^[23]

Fig. 6. Typical structure of “9-type cavity”^[31]

Fig. 7. Structural diagram of laser with long “9-type cavity”^[32]

Fig. 8. Experimental setup of laser with “9-type cavity” and Faraday rotator^[36]

Fig. 9. Structural diagram of compact “9-‍type cavity” laser based on all polarization maintaining fiber,and structural diagram of reflection-‍type phase shifter^[37]. (a) Structural diagram of compact “9‍-‍type cavity” laser based on all polarization maintaining fiber; (b) structural diagram of reflection⁃type phase shifter

Fig. 10. Structure of dispersion managed “9-type cavity”^[40]

Fig. 11. Structure of spatiotemporal mode-locking fiber laser^[42]

Fig. 12. Mode distribution in spatiotemporal mode-locked laser cavities supporting multiple transverse modes^[4]

Fig. 13. Spatiotemporal mode-locked fiber laser based on all multimode fiber^[42]

Fig. 14. Peak and average powers of femtosecond fiber laser^[46]

Fig. 15. Schematic diagram of ultrafast pulse spatial combination system

Fig. 16. Coherent combination setup based on DOE^[51]

Fig. 17. Principle of beam division based on birefringent crystal^[52]

Fig. 18. Enhanced stacking amplification technique in pulse cavity with high Q^[54]

Fig. 19. Principle diagram of GTI^[55]