Fig. 1. (a) Schematic setup of an SWNT-based polarization multiplexing fiber laser. WDM, wavelength division multiplexer; OC, optical coupler; PI-ISO, polarization-insensitive isolator; PC, polarization controller; SWNT SA, single-walled carbon nanotube saturable absorber; EDF, erbium-doped fiber; SMF, single-mode fiber; PBS, polarization beam splitter; (b) FESEM analysis of SWNT; and (c) Raman analysis of SWNT taken at 532 nm excitation.

Fig. 2. Dual-comb state output information. (a) Output spectrum information; (b) RF spectrum with the resolution bandwidth of 1 Hz; (c) temporal information.

Fig. 3. Output characteristics of soliton rain. (a) Output spectrum information; (b) temporal information; (c), (d) detailed description of soliton rain pulse.

Fig. 4. RF and autocorrelation information in dual-comb mode-locking state. (a) RF spectrum of the dual-comb ultrashort pulses; (b) autocorrelation trace of output pulse and sech² fitting.

Fig. 5. (a) Spectral information of seed source and polarized light, and (b)–(d) RF spectra of seed source and polarized light.

Fig. 6. Time domain and autocorrelation information of seed source and two polarization directions. (a), (b), (c) Asynchronous pulse sequence; (d), (e), (f) autocorrelation trace and sech² fitting.

Fig. 7. Change in the number of isolating solitons under different pump currents and different PC angles. (a)–(d) Different pump currents; (e)–(h) different PC angles.

Fig. 8. Evolutions of soliton rain state (a) with four isolating solitons, and (b) with nine isolating solitons within 30 min.