Facile Synthesis of 2D Tin Selenide for Near- and Mid-Infrared Ultrafast Photonics Applications

Tin selenide (SnSe) nanosheets, as 2D materials, exhibit many excellent optical and electronic properties and can be widely utilized in various potential applications, such as photodetectors, photovoltaic cells, optical sensors, and nonlinear optical devices. Herein, the 2D SnSe nanosheets are synthesized by the method combining lithium ion intercalation and sonication-assisted liquid phase exfoliation. The morphology, structures, and chemical composition of as-prepared 2D SnSe sample are systemically analyzed. Interestingly, the 2D SnSe nanosheets are successfully fabricated as a saturable absorber (SA) by depositing on a microfiber, which shows excellent nonlinear absorption property in a wide band. By incorporating SnSe-based SA into the fiber lasers, stable mode-locked pulses can be realized at 1.5 and 2 µm with a pulse duration of 0.542 and 2.12 ps, respectively. Additionally, harmonic mode locking of bound solitons is generated in the 1.5 µm fiber laser. Furthermore, dual-wavelength mode-locked pulses at 1897.3 and 1910.5 nm are also obtained in the 2 µm fiber laser. These results validate that 2D SnSe materials show great potential in nonlinear photonic devices for broadband ultrafast photonics.