Vanadium disulfide for ultrafast photonic application.

The investigation of two-dimensional (2D) nonlinear optical materials offers a promising way to construct the high-performance optical devices in fundamental and industrial applications because of their rich distinct optoelectronic properties. Herein, by utilizing the liquid exfoliation method, vanadium disulfide (VS) nanosheets are prepared and the thickness is measured to be 3.16 nm. In addition, we have fabricated the VS-based optical device and the nonlinear optical property is characterized with modulation depth of 23.97%. By using VS as saturable absorber, a high stable passively mode-locking Er-doped fiber laser is obtained with pulse duration of 169 fs and the largest average output power of 70.5 mW. The slope efficiency is up to 7.9%. In comparison to recent results of mode-locking fiber lasers with 2D materials, the VS-based fiber laser demonstrates better performance. To the best of our knowledge, this is the first example of using VS for generating femtosecond mode-locked laser pulse. Our experimental results not only reveal VS ultrafast photonics application, but also advance the high-performance applications for information science and nonlinear optics.