Fig. 1. Experimental structure of picosecond pulse nonlinear amplifier

Fig. 2. Passively mode-locked fiber laser output spectra and auto-correlation curve

Fig. 3. Output spectrogram of amplifier1

Fig. 4. Spectrogram of amplifier2 at different output power

Fig. 5. Curve of SC output power versus the pump power

Fig. 6. Variation curve of return light of different seed signals with pump power

Fig. 7. Output spectrogram of different pump power of amplifier2