Fig. 1. Theoretical model of ANDi NPR mode-locked fiber laser

Fig. 2. Numerical simulation results of ANDi NPR mode-locked fiber laser. (a) Evolution of output laser; (b) evolution of intra-cavity spectrum of stable state (at 400 roundtrip); (c) evolution of intra-cavity pulse of stable state (at 400 roundtrip); (d) evolution of intra-cavity pulse energy at 400 roundtrip

Fig. 3. Schematic of 1024 nm Yb-doped fiber MOPA system based on NPR mode-locked. (a) Seed source laser; (b) pre-amplifier; (c) main amplifier

Fig. 4. Output pulse characteristics of oscillator. (a) Output power varies with pump power; (b) spectral evolution under different pump powers; (c) AC trace when pump power is 375 mW; (d) RF spectrum when pump power is 375 mW

Fig. 5. Establishment process of DS state. (a) Experimental results; (b) simulation results

Fig. 6. Output results after tunable filter. (a) Spectrum at different wavelengths; (b) output pulse sequence at 1024 nm

Fig. 7. Output pulse characteristics of laser pre-amplifier. (a) Output power curve; (b) output spectrum evolution under different pump powers; (c) pulse autocorrelation curve; (d) RF spectrum

Fig. 8. Output pulse characteristics of main amplifier. (a) Output power curve change with pump power after amplification; (b) output spectrum under different pump powers; (c) pulse sequence when pump power is 5 W; (d) RF spectrum when pump power is 5 W