Fig. 1. Structural diagram of low-repetition-rate high-energy all-fiber picosecond pulse MOPA device

Fig. 2. Structural diagram of 1560 nm LD device

Fig. 3. Output pulse characteristics of seed source. (a) Pulse width; (b) spectrum; (c) time-domain pulse trace; (d) frequency spectrum

Fig. 4. Pulse output after pre-amplification. (a) Output power of preamplifier versus pump power; (b) pulse spectrum at preamplifier output with pump power of 573 mW

Fig. 5. Temporal pulse traces under different repetition rates after pulse picking. (a) 2 MHz; (b) 100 kHz; (c) 50 kHz; (d) 20 kHz

Fig. 6. Output pulse spectra

Fig. 7. Pulse output after main amplification. (a) Spectrum; (b) pulse width

Fig. 8. Output power at main amplifier versus pump power of second-stage amplifier at minimum repetition rate of 20 kHz

Fig. 9. Output power stability