5. Conclusion

The compactness and efficiency of fiber lasers, combined with remarkable performance in terms of power and beam quality, have led to a large number of applications, both scientific and industrial. In particular, the technology of ytterbium-doped fibers is now industrially mature, and the performance of transverse single-mode laser sources achieved in the laboratory with these fibers seems to be fairly close to fundamental physical limits, whether in continuous or pulsed mode. Future advances in source performance could come from new fiber technologies, and in particular from the search for large-modal-area structures that are less sensitive to the external environment. Transposing the excellent performance of ytterbium-doped fiber lasers to other wavelength ranges, either by using other dopants such as thulium or erbium, or by external wavelength conversion, also seems an important challenge...