Fig. 1. Experimental setup of the passively mode-locked all-PM fiber laser. LD, laser diode; WDM, wavelength division multiplexer; CFBG, chirped fiber Bragg grating; YDF, Yb-doped fiber; SMF, single-mode fiber; SESAM, semiconductor saturable absorber mirror; HWP, half-wave plate; PBS, polarization beam splitter; ISO, isolator.

Fig. 2. Spectral width at 10 dB (red solid squares) and dechirped pulse width at 3 dB (blue open circles) of the output pulses versus the NCD at a pump power of (a) 80 mW, (b) 90 mW, (c) 100 mW, (d) 110 mW, (e) 120 mW, and (f) 130 mW (gray area: multi-pulsing region).

Fig. 3. (a) Spectrum and autocorrelation trace of soliton molecules at 80 mW pump power. (b) Spectra of single soliton states for two critical NCD values at 80 mW pump power (gray area: CFBG reflection spectrum).

Fig. 4. Autocorrelation traces of dechirped output pulses (blue solid lines) and Gaussian fitting curves (red dashed lines) at a pump power of (a) 80 mW, (b) 100 mW, and (c) 130 mW. Insets: corresponding spectra of output pulses.

Fig. 5. (a) Schematic of the numerical simulation model. Evolution of spectral width (red solid line) and temporal width (blue dotted line) when the NCD is for (b) β_net = −1.1 × 10⁻³ ps² and (c) β_net = +1.5 × 10⁻² ps². YDF, Yb-doped fiber; SMF, single-mode fiber; SESAM, semiconductor saturable absorber mirror; DCF, dispersion compensating fiber; OC, optical coupler.

Fig. 6. (a) FWHM spectral width of output pulses as a function of NCD and E_sat. Linear scale: 4 nm 20 nm (white area: multi-pulsing region). (b) FWHM spectral width of pulses at point D as a function of filter bandwidth and E_sat. Linear scale: 8 nm 16 nm (white area: multi-pulsing region). (c) FWHM spectral width of pulses at the OC (red open squares) and at point D (red open-triangles) at critical pump power and corresponding E_sat (blue solid circles).