An all-fiber, resonantly pumped, gain-switched, 2 μm Tm-doped silica fiber laser

An all-fiber, gain-switched, single-mode, thulium-doped silica fiber laser operating at a wavelength of 1994.6 nm was developed. The laser was pumped by a 1.55 μm master oscillator power amplifier (MOPA) system and operated at a repetition rate ranging from 50 to 300 kHz. Different configurations of the laser cavity were tested. When operating at a 100 kHz repetition rate the laser delivered a maximum average power as high as 1.08 W with a slope efficiency of 49%. For a repetition rate of 50 kHz, stable 23 ns pulses with an energy of 15.3 μJ, corresponding to a peak power of 623 W, were achieved. We also report, to the best of our knowledge, the first demonstration of 2 μm gain-switched, mode-locked pulses with 100% modulation depth obtained in a Tm-doped fiber laser.