Niobium telluride absorber for a mode-locked vector soliton fiber laser

Niobium telluride (NbTe2), an emerging transition metal dichalcogenide material, has been theoretically predicted to have nonlinear absorption properties and excellent optical response. However, only a few studies of the utilization of NbTe2 in ultrafast photonics have been reported. In this work, a NbTe2-based saturable absorber (SA) was applied in an erbium-doped fiber as a mode-locked device, and a vector soliton based on NbTe2 was obtained for the first time. NbTe2-PVA film SA was successfully prepared by the liquid-phase exfoliation and spin coating methods, with a modulation depth of up to 10.87%. The nonlinear absorption coefficient of NbTe2-based SA film tested through the open-aperture Z-scan laser measurement is 0.62 x 10 (-11) m/W. A conventional soliton with a pulse duration of 858 fs was generated using NbTe2-based SA, which was demonstrated to be a kind of polarization-locked vector soliton in further investigation. Our experimental results reveal the nonlinear optical properties of NbTe2 and broaden its applications in ultrafast photonic devices.