The usage of W _x Nb _(1−x) Se ₂ nanosheets as a rising ultrafast photonic device to generate high power mode-locked and Q-switched pulses in a fiber laser is demonstrated.

In this Letter, we focus on investigating the ultrafast photonics applications of two-layer HfS₃ nanosheets. We prepared two-layer HfS₃ nanosheets and carried out experiments to study their nonlinear saturable absorption properties. The results showed that the two-layer HfS₃-based saturable absorber exhibited a modulation depth of 16.8%. Additionally, we conducted theoretical calculations using first principles to estimate the structural and electronic band properties of the two-layer HfS₃ material. Furthermore, we utilized the two-layer HfS₃ materials as SAs in an erbium-doped fiber cavity to generate mode-locked laser pulses. We measured a repetition frequency of 8.74 MHz, a pulse duration of 540 fs, and a signal-to-noise ratio of 77 dB. Overall, our findings demonstrate that the two-layer HfS₃ material can serve as a reliable saturable absorber, possessing properties comparable to currently used two-dimensional materials. This expands the application fields of HfS₃ materials and highlights their potential for advanced optoelectronic devices.

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 ₂ ) nanosheets are prepared and the thickness is measured to be 3.16 nm. In addition, we have fabricated the VS ₂ -based optical device and the nonlinear optical property is characterized with modulation depth of 23.97%. By using VS ₂ 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 ₂ -based fiber laser demonstrates better performance. To the best of our knowledge, this is the first example of using VS ₂ for generating femtosecond mode-locked laser pulse. Our experimental results not only reveal VS ₂ ultrafast photonics application, but also advance the high-performance applications for information science and nonlinear optics.