Fig. 1. 2-4 μm mid-infrared fiber lasers doped with rare-earth ions. (a) Typical structure of rare-earth doped mid-infrared fiber laser; (b) emission spectra at 2-4 µm band for different transition processes in Tm³⁺/Ho³⁺/Er³⁺/Dy³⁺-doped silica/fluoride glass^[12]; (c) corresponding energy level transition processes

Fig. 2. 1100 W cladding-pumped thulium-doped all-fiber amplifier^[26]. (a) Laser system; (b) slope efficiency; (c) spectrum at 1.1 kW output power

Fig. 3. High-power dual-end pumped Er³⁺∶ZBLAN all-fiber laser^[27]. (a) Laser system; (b) slope efficiency; (c) output spectra

Fig. 4. High-power 2.9 μm holmium-doped fiber laser^[28]. (a) Laser system; (b) slope efficiency; (c) output spectrum; (d) wavelength tunability

Fig. 5. High-power all-fiber 3.24 μm dysprosium-doped fiber laser^[29]. (a) Laser system; (b) spectra of high/low reflectivity FBGs; (c) slope efficiency

Fig. 6. High-power all-fiber 3.55 μm erbium-doped fiber laser^[52]. (a) Laser system; (b) slope efficiency and output power

Fig. 7. 3.92 μm Ho³⁺-doped fiber laser^[55]. (a) Laser system; (b) energy level diagram; (c) slope efficiency and output power

Fig. 8. Cascaded Raman pulsed fiber laser pumped by actively modulated Q-switched pulses^[84]. (a) Laser system; (b) laser output spectra at maximum pumping power when pump wavelengths are 2.008 μm and 2.04 μm, respectively

Fig. 9. 2231 nm Raman fiber laser with nested cavity structure based on fluoride glass fiber^[89]. (a) Experimental setup; (b) output power of 2231 nm Raman laser versus pump power

Fig. 10. Output power versus pump power^{with output spectrum at pump power of 491.5 mW shown in inset[90]}

Fig. 11. 3.77 μm cascaded Raman fiber laser based on As₂S₃ fiber^[93]. (a) Experimental setup; (b) average output power and peak power of 3.77 μm Stokes light versus pump power when reflectivity values of output coupler are 98%, 92%, and 80%, respectively

Fig. 12. Tunable mid-infrared Raman soliton fiber laser based on InF₃ glass fiber^[103]. (a) Experimental setup; (b) spectra of redshifted soliton at different wavelengths in 2 m long InF₃ glass fiber

Fig. 13. Tunable mid-infrared Raman soliton fiber laser based on Er-doped zirconium fluoride fiber^[102]. (a) Experimental setup; (b) SSFS spectra in 22 m long Er-doped zirconium fluoride fiber

Fig. 14. Tunable mid-infrared Raman soliton fiber laser based on InF₃ fiber^[111]. (a) Experimental setup; (b) output spectrum of InF₃ fiber at 70 W pump power

Fig. 15. Schematic of flat supercontinuum laser generation based on NL1550 fiber and indicators^[116]. (a) Experimental setup; (b) output power versus pump power; (c) output spectra of NL1550 fiber at different pump powers

Fig. 16. Supercontinuum laser generation diagram and spectral results based on germanate fiber^[122]. (a) Experimental setup; (b) output spectra of 20 cm long germania fiber at different pump powers

Fig. 17. Supercontinuum laser system pumped by noise-like pulses^[128]. (a) Experimental setup; (b) output spectrum evolution with pump power ; (c) output power versus pump power at different pulse widths

Fig. 18. High power fluorotellurite fiber supercontinuum laser^[133]. (a) Experimental setup; (b) spectra of fluorotellurite fiber at different output powers; (c) output power versus pump power

Fig. 19. Supercontinuum laser based on 1.9-4.9 μm InF₃ fiber^[136]. (a) Experimental setup; (b) supercontinuum spectrum based on InF₃ fiber