Fig. 1. Visible laser sources and their available wavelengths^[12]

Fig. 2. Energy levels of rare-earth-doped fluoride fiber^[28-35]. (a) Energy levels of Pr³⁺-doped fluoride fiber; (b) energy levels of Dy³⁺-doped fluoride fiber; (c) energy levels of Tb³⁺-doped fluoride fiber; (d) energy levels of Ho³⁺-doped fluoride fiber; (e) energy levels of Tm³⁺-doped fluoride fiber; (f) energy levels of Pr³⁺/Yb³⁺-doped fluoride fiber

Fig. 3. Ho³⁺∶ZBLAN high power CW fiber lasers^[50]. (a) Experimental setup; (b) tunable spectrum; (c) line width of 543.1 nm laser; (d) slope efficiency

Fig. 4. Deep red tunable CW fiber lasers^[62]. (a) Experimental setup; (b) tunable spectra

Fig. 5. High power deep red CW fiber lasers^[67]. (a) Experimental setup; (b) physical picture; (c) slope efficiency; (d) spectrum

Fig. 6. Red CW fiber lasers^[64]. (a) Experimental setup; (b) slope efficiency; (c) spectrum

Fig. 7. All-fiber red CW fiber lasers^[65]. (a) Experimental setup; (b) slope efficiency; (c) spectrum

Fig. 8. High power red CW fiber lasers^[69]. (a) Experimental setup; (b) slope efficiency; (c) spectrum; (d) beam quality; (e) power stability

Fig. 9. High power yellow CW fiber lasers^[74]. (a) Experimental setup; (b) physical picture ; (c) slope efficiency; (d) spectra

Fig. 10. Green CW fiber lasers^[71]. (a) Experimental setup; (b) slope efficiency; (c) spectrum

Fig. 11. High power green CW fiber lasers^[79]. (a) Experimental setup; (b) physical picture ; (c) slope efficiency; (d) spectrum

Fig. 12. Graphene orange passively Q-switched fiber lasers^[96]. (a) Experimental setup; (b) Q-switched pulse train; (c) slope efficiency

Fig. 13. Green Q-switched vortex fiber lasers^[94]. (a) Experimental setup; (b) output spectrum; (c) pulse trains; (d) intensity distributions of high order modes

Fig. 14. Visible all-fiber passively mode-locked lasers^[101]. (a) Experimental setup; (b) mode-locked spectrum; (c) pulse train; (d) single pulse; (e) radio-frequency spectrum

Fig. 15. Visible spatiotemporal mode-locked lasers^[103]. (a) Experimental setup; (b) mode-locked pulse trains; (c) mode-locked spectra; (d) amplified power and pulse energy; (e) radio-frequency spectrum

Fig. 16. Yellow passively mode-locked fiber lasers^[104]. (a) Pulse train with narrow span; (b) pulse train with large span; (c) evolution of single pulse envelope with pump power; (d) autocorrelation trace; (e) experimental setup

Fig. 17. External cavity compressed visible femtosecond fiber lasers^[28]. (a) Experimental setup; (b) mode-locked spectrum; (c) mode-locked autocorrelation trace

Table 1. Representative research achievements of up-conversion visible CW fiber lasers

Table 2. Representative research achievements of down-conversion visible CW fiber lasers

Table 3. Representative research achievements of visible passively Q-switched fiber lasers

Table 4. Representative research achievements of visible passively mode-locked fiber lasers