Fig. 1. Structure diagram of 1120 nm Q-switched fiber laser^[22]

Fig. 2. Active Q-switched ring cavity fiber laser. (a) Schematic diagram of structure; (b) Change of pulse width and pulse energy at different repetition frequencies; (c) Spectra, illustrated in logarithmic coordinates^[24]

Fig. 3. Nanosecond pulse obtained by EOIM modulated continuous wave^[27]

Fig. 4. Passive Q-switched laser with Ytterbium-doped fiber as saturable absorber^[34]

Fig. 5. Fiber laser with SMS structure^[36]

Fig. 6. Structure diagram of passive Q-switched fiber laser with double cavity compound structure^[38]

Fig. 7. Schematic diagram of gain-switched nanosecond pulse fiber laser^[40]

Fig. 8. Low repetition rate nanosecond pulse amplifier and its synchronous pulse pumping technology. (a) Schematic diagram of all-fiber MOPA structure; (b) Time series of pump pulses at different amplification stages

Fig. 9. Nearly kilowatt average power laser amplifier. (a) Schematic of structure; (b) Curve of average power vs. pump power; (c) Spectral pattern^[54]

Fig. 10. All-fiber linearly polarized MOPA laser system. (a) Structural diagram; (b) 6 spots randomly collected during the maximum power output, indicating that TMI appears ^[27]

Fig. 11. All-fiber sub-nanosecond laser amplifier and its output characteristics. (a) Schematic of structure; (b) Changes of beam quality at 976 nm pumping wavelength; (c) Changes of beam quality at 915 nm pumping wavelength. The improvement of beam quality shows that TMI is suppressed^[56]

Fig. 12. Output characteristics of fiber amplifier. (a) Amplifier construction with an average power of 300 W; (b) Curve of average power vs. pump power; (c) Display of laser cleaning^[61]

Fig. 13. 1000 W all-fiber laser system ^[63]