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.

Group VB transition metal dichalcogenides (TMDCs) are emerging two-dimensional materials and have attracted significant interests in the fields of physics, chemistry, and material sciences. However, there are very few reports about the optical characteristics and ultrafast photonic applications based on group VB TMDCs so far. In this work, we have calculated the niobium disulfide (NbS₂) band structure by the density functional theory (DFT), which has revealed that NbS₂ is a metallic TMDC. In addition, we have prepared an NbS₂-microfiber device and the nonlinear optical characteristics have been investigated. The modulation depth, saturation intensity and non-saturable loss have been measured to be 13.7%, 59.93 MW cm⁻² and 17.74%, respectively. Based on the nonlinear optical modulation effect, the Er-doped fiber (EDF) laser works in the soliton mode-locking state with the pump power of 94–413 mW. The pulse duration of 709 fs and the maximum average output power of 23.34 mW have been obtained at the pump power of 413 mW. The slope efficiency is as high as 6.79%. Compared to the recently reported studies based on TMDCs comprehensively, our experimental results are better. These experimental results demonstrate that NbS₂ with excellent nonlinear optical properties can be used as a promising candidate to advance the development of ultrafast photonics.

In this work, we investigate VSe₂ for generating femtosecond and large energy mode-locked laser pulses for the first time.

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.