All-fiber wavelength-widely tunable multi-pulse gain-switched Tm3+-doped double-clad fiber laser

• We report a multi-pulse gain-switched Tm 3+ -doped fiber laser with 793 nm pump source. • Tm 3+ -doped double clad fiber provides large laser gain, the single-pulse energy can reach 4.3 μJ and the multi-pulse energy can be 13.2 μJ. • The all-fiber structure gain switched TDCFL has a wide wavelength tunable range of 1944–2049 nm. • The larger pulse energy, the higher repetition rate and the longer pulse duration of the pump source will be easier to lead to multi-pulse phenomenon. We report a wavelength-widely tunable multi-pulse gain-switched Tm 3+ -doped fiber laser. The laser has a continuous wavelength-tunable range of 105 nm in 2 μm band. The combination of Tm 3+ -doped double clad fiber and 793 nm pulsed pump source achieves large-energy pulse and multi-pulse operation. The single-pulse energy can reach 4.3 μJ and the multi-pulse energy can be 13.2 μJ. The effects of pump pulse energy, pulse repetition rate and pulse duration on multi-pulse generation are studied in detail. This easy-to-operate large-energy 2 μm pulsed fiber laser with adjustable pulse duration and repetition rate can provide a stable single-pulse or multi-pulse source in spectroscopy, medical surgery, material processing, etc.