Magnetron-sputtering deposited WTe_2for an ultrafast thulium-doped fiber laser

Ultrafast pulse generation was demonstrated in a thulium-doped fiber laser mode-locked by magnetron-sputtering deposited WTe₂ with a modulation depth, a nonsaturable loss, and a saturable intensity of 31%, 34.3%, and 7.6 MW/cm², respectively. Stable soliton pulses could be obtained at a 1915.5 nm central wavelength with a pulse duration of 1.25 ps, an average output power of 39.9 mW, and a signal-to-noise ratio of 95 dB. To the best of our knowledge, this was the first demonstration of WTe₂-based saturable absorbers in fiber lasers at a 2 μm regime.