Fig. 1. Schematic of the experimental setup. (a) Simplified NPR mode-locked Yb-doped fiber laser. (b) DFT system. WDM, wavelength division multiplexer; YDF, Yb-doped fiber; OC, output coupler; ISO, isolator; PBS, polarized beam splitter; C1, C2, collimators; PD, photodetector.

Fig. 2. Corresponding mode-locking states at different tilt angles of PBS in the cavity (±5°).

Fig. 3. Output characteristics of DS and NLP at a pump power of 560 mW. (a) Spectrum of DS. (b) Spectrum of NLP. (c) and (d) show the autocorrelation traces corresponding to (a) and (b), respectively.

Fig. 4. Last frame of the spectrum of (a) DS and (b) NLP in the real-time sequences measured with the DFT technique. Inset: the entire evolution process.

Fig. 5. Real-time spectral evolution during the formation of DS. (a) Entire buildup dynamics process. (b) 0–2500 round trips in (a), which contains the QS and RO processes. (c) Successive soliton explosions during 4000–6000 round trips in (a). (d) Soliton breathing and soliton explosion in the final stage of buildup stable DS. (e) Single-frame spectrum derived from 7500 round trips in (a).

Fig. 6. Real-time spectral evolution dynamics during the formation of NLP. (a) Entire buildup dynamics process. (b) The NLP spectrum after different round trips (RTs) in an evolution period.

Fig. 7. Ensemble average of the spectra within the last 500 round trips in Fig. 6(a).

Fig. 8. Real-time spectral evolution dynamics during the formation of DP (for DS). (a) The birth dynamics process of DP. (b) QS and RO in the early stages of evolution for (a). (c) Soliton breathing in dynamics process. (d) The birth dynamics process of coexisting sub-pulse and adjacent main pulse.

Fig. 9. Real-time spectral evolution dynamics during the formation of DP (for NLP). (a) The DP birth dynamics process of NLP. (b) The birth dynamics process of the sub-pulse with the next main pulse.

Fig. 10. Entire inter-conversion process of DS and NLP. (a) Conversion from DS to NLP. (b) Conversion from NLP to DS.