High energy all-fiber based pulsed thulium-doped fiber laser at 2 μm

A stable high energy all-fiber based pulsed thulium-doped fiber laser at 2 m is obtained based on gain-switched techniques. The pulse repetition rate can be tuned between 10 kHz and 50 kHz, and the central wavelength of the laser is 1958 nm. With the rise of injected pump power, the output pulse width decreases and is in a range of 1.2-1.7 s. By using two-stage thulium-doped fiber amplifiers the average output power is scaled up to 5.18 W at 10 kHz, the output pulse width is 1.6 s, and the corresponding single pulse energy after amplification is 0.518 mJ.