Hybrid-pumped, gain-switching operation of a Tm-doped fiber laser with linear-polarized output

We report an all-fiber laser with a linear-polarized, pulsed 2 μm output up to 4.6 W by applying a hybrid-pump gain-switched scheme. In this method, a 790 nm laser diode serves as the main supplier of inverse population while a 1 μm pulsed Yb-doped fiber laser triggers the 2 μm pulsed lasing, to realize the gain-switching operation. We construct a resonant cavity with a polarization-maintaining Tm-doped fiber and a fiber Bragg grating to achieve a polarized laser. The laser output is centered at 2021 nm and has a polarization extinction ratio of 13.7 dB; the maximum pulse energy is 230 μJ at a repetition rate of 20 kHz. (letter)