Fig. 1. Configuration of spatiotemporal mode-locked fiber laser

Fig. 2. Experimental results of few-mode STML laser. (a) Spectra of different beam profiles; (b) time-domain pulses of different beam profiles; (c) fundamental frequency RF spectrum with RF spectrum in 0‒1 GHz shown in inset; (d) pulse splitting

Fig. 3. Evolution of beam profile and output power versus pump power. (a)(b) Evolution of beam profile; (c) output power versus pump power

Fig. 4. Experimental results of multimode STML laser. (a) Spectra at 4 μm and 8 μm fusion misalignment amounts; (b) mode-locked time domain pulse at 8 μm fusion misalignment amount; (c) RF spectrum at 8 μm fusion misalignment amount; (d) single pulse output power versus pump power

Fig. 5. Beam profile evolution at 4 μm and 8 μm fusion misalignment amounts. (a) 4 μm fusion misalignment amount; (b) 8 μm fusion misalignment amount

Fig. 6. Three-dimensional distribution maps of beam intensity and Gaussian fitting curves of cross sections under different fusion misalignment amounts. (a) 4 μm fusion misalignment amount; (b) 8 μm fusion misalignment amount

Fig. 7. Two mode-locking states. (a) Second-order harmonic; (b) three pulses