Ultrathin 2D Nonlayered Tellurene Nanosheets as Saturable Absorber for Picosecond Pulse Generation in All-Fiber Lasers

Tellurene is a new 2D nonlayered material, which have obvious structural differences in both horizontal and vertical directions compared to layered materials. However, photonic devices related to its nonlinear optical characteristics are currently less studied. Herein, ultrathin 2D tellurene nanosheets were harvested from bulk tellurium crystals by liquid-phase exfoliation method. The low saturable intensity (1.06 MW/cm 2 ) and the high modulation depth (35.64%) of tellurene nanosheets were characterized by two-arm detection technology. To the best of our knowledge, this is the first attempt to utilize tellurene-microfiber as a saturable absorber, and achieved a picosecond passive mode-locked erbium-doped fiber laser. Stable picosecond pulses were generated at 1558.8 nm with a pulse duration of 1.03 ps. This work highlights the promise of 2D tellurene in short pulse lasers and will promote the applications of 2D nonlayered materials in ultrafast photonics.