In this paper, tin disulfide (${\mathrm{SnS}}_2$), a two-dimensional (2D) n-type direct bandgap layered metal dichalcogenide with a gap value of 2.24 eV, was employed as a saturable absorber. Its appearance and nonlinear saturable absorption characteristics were also investigated experimentally. ${\mathrm{SnS}}_2\text{-}\mathrm{PVA}$ (polyvinyl alcohol) film was successfully prepared and employed as a mode-locker for achieving a mode-locked Er-doped fiber laser with a pulse width of 623 fs at a pulse repetition rate of 29.33 MHz. The results prove that ${\mathrm{SnS}}_2$ nanosheets will have wide potential ultrafast photonic applications due to their suitable bandgap value and excellent nonlinear saturable absorption characteristics.

Two‐dimensional layered monoelemental materials (Xenes) with excellent optoelectronic properties have various property‐related applications, such as energy, biomedicine, and optoelectronic devices. Xenes also show excellent performance in acting as saturable absorbers (SAs) for obtaining ultrafast laser operations. Few‐layer tellurene as a typical Xenens exhibits distinct optoelectronic properties and promising practical application potential, and its nonlinear optical absorption characteristics and related ultrafast modulation applications have been investigated preliminarily. However, tellurene‐based SAs to demonstrate large‐energy mode‐locked operations, which have special applications in industrial and scientific research areas, are seldom studied. In this work, we focus on the preparation of tellurene‐based SAs and explore its applications in demonstrating large‐energy mode‐locked operations [dissipative soliton (DS) and noise‐like pulses (NLP)]. For DS operation, the maximum average output power, pulse width, and largest pulse energy are 23.61 mW, 5.87 ps, and 1.94 nJ, respectively. NLP operation with a recorded average output power of 106.6 mW and a pulse energy of 8.76 nJ is also generated, which shows significant enhancement in comparison to previously reported Xenes‐based works. Our contribution reveals the great potential and capacity of tellurene‐based SAs in obtaining large‐energy pulse operations and further promotes the explorative investigation of Xenes‐based optoelectronic devices.

Layered transition metal dichalcogenides with excellent nonlinear absorption properties have shown remarkable performance in acting as ultrafast photonics devices. In our work, palladium diselenide (PdSe ₂ ) nanosheets with competitive advantages of wide tunable bandgap, unique puckered pentagonal structure and excellent air stability are prepared by the liquid‐phase exfoliation method. Its ultrafast absorption performance was verified by demonstrating conventional and dissipative soliton operations within Er‐doped fiber lasers. The minimum pulse width of the conventional soliton was 1.19 ps. Meanwhile, dissipative soliton with a 46.67 mW output power, 35.37 nm spectrum width, 14.92 ps pulse width and 2.86 nJ pulse energy was also generated successfully. Our enhanced experiment results present the excellent absorption performance of PdSe ₂ and highlight the capacity of PdSe ₂ in acting as ultrafast photonics devices.

In our work, Bi₂Se₃ was successfully used for demonstrating a large-energy passively Q-switched erbium-doped fiber laser. Bi₂Se₃ nanosheets were fabricated by a catalyst-free chemical vapor deposition method. Based on a pyrolysis tape transfer method, the Bi₂Se₃ thin film on the SiO₂ substrate was transferred to the end of the optical connector for constructing the fiber-integrated saturable absorber. The saturation intensity and modulation depth of the Bi₂Se₃ saturable absorber were 81.1 MW/cm² and 15.7%, respectively. A stable Q-switched operation at 1549.99 nm with a maximum average output power of 23.61 mW was achieved. The minimum pulse duration and the largest pulse energy were 1.34 μs and 224.5 nJ, respectively. In comparison with previous works, the single pulse energy (224.5 nJ) obtained in our experiment was improved significantly. Our experimental results fully proved that CVD-Bi₂Se₃ has good performance in obtaining large energy pulse operations and will promote the applications of 2D CVD-materials in the field of pulse laser.

Layered metal dichalcogenides (LMDs) have been extensively employed as saturable absorbers (SAs) for demonstrating passively Q-switched or mode-locked lasers due to the advantages of wide absorption range and ultra-fast recovery time. In this paper, the nonlinear saturable absorption property of another IV-VI LMDs tin disulfide (SnS₂) was investigated. SnS₂-polyving alcohol (PVA) film was successfully prepared and employed as a SA for demonstrating an Er-doped passively Q-switched fiber laser. Under a pump power of 637 mW, the maximum average output power was 9.33 mW. The minimum pulse width was as narrow as 510 ns, which, to our knowledge, is the narrowest pulse width obtained within passively Q-switched Er-doped all-fiber ring-cavity lasers. The results indicate that film-type SnS₂-PVA SA has excellent nonlinear absorption properties and outstanding performance in obtaining short-pulse passively Q-switched operation, which will promote the practical applications of SnS₂ in the field of ultrafast photonics.

Driven by new two‐dimensional materials, great changes and progress have taken place in the field of ultrafast photonics in recent years. Among them, the emerging single element two‐dimensional materials (Xenes) have also received much attention due to their special physical and photoelectric properties including tunable broadband nonlinear saturable absorption, ultrafast carrier recovery rate, and ultrashort recovery time. In this review, the preparation methods of Xenes and various integration strategies are detailedly introduced at first. Then, we summarize the outcomes achieved by Xenes‐based (beyond graphene) fiber lasers and make classifications based on the characteristics of output pulses according to the materials characterization and nonlinear optical absorption properties. Finally, an outlook of the future opportunities and challenges of ultrafast photonics devices based on Xenes and other 2D materials are highlighted, and we hope this review will promote their extensive applications in ultrafast photonics technology.