Fig. 1. Multimode interference filter model and filtering characteristics. (a) Structure schematic of fiber filter; (b) filter characteristics of GIMF at a stretch length of 4.84 μm

Fig. 2. Simulation results of different pulse temporal intensity waveforms. (a) Gaussian pulse; (b) parabolic pulse; (c) Lorentz pulse; (d) triangular pulse

Fig. 3. Schematic setup of mode-locked fiber laser

Fig. 4. Output characterizations of traditional soliton mode-locked pulses. (a) Output spectrum; (b) temporal train of pulse;

Fig. 5. Traditional soliton mode-locked pulses. (a) Output spectrum and (b) radio frequency spectrum fluctuation in 24 h; (c) variations in the center wavelength, output power, and repetition frequency of traditional soliton mode-locked pulses with time

Fig. 6. Output characteristics of stretched pulse and self-similar pulse. (a) Output spectrum of stretched pulse; (b) output spectrum of self-similar pulse; (c) autocorrelation curve of stretched pulse; (d) autocorrelation curve of self-similar pulse

Fig. 7. Output characteristics of Lorentz and triangular pulses. (a) Output spectrum of Lorentz pulse; (b) output spectrum of triangular pulse; (c) autocorrelation curve of Lorentz pulse; (d)(e) autocorrelation curve of triangular pulse and its trajectory in a wider range

Fig. 8. 24 h continuous monitoring of variations in the spectral center wavelength for four types of output pulses