Research Progress of High Power Continuous Wave Thulium-Doped Fiber Laser

In recent years, Thulium- doped fiber laser has attracted more and more attention because of its compact structure, near diffraction limit beam quality, and high quantum efficiency. Among these laser sources, high power continuous wave (CW) thulium-doped fiber lasers have been widely used in many fields, such as medical treatment, military security, space communication, air pollution detection, material processing, and so on. In the past 20 years, high power CW thulium- doped fiber lasers have developed rapidly, and the highest output power has reached kilowatt level. In this paper, the high power CW thulium- doped fiber lasers reported in the past are reviewed from the aspects of oscillator and amplification system, and some views on the future development trend are given.