Two-dimensional (2D) tin diselenide ($\mathrm{Sn}{\mathrm{Se}}_2$), a novel layered material with excellent optical and electronic properties, has been extensively investigated in various promising applications, including photodetectors, optical switching, and ultrafast photonics. In this work, $\mathrm{Sn}{\mathrm{Se}}_2$ nanosheets have been obtained after pretreatment in an alkaloid, exhibiting high optical absorption and electron-enriched properties. Besides, the performances of the prepared $\mathrm{Sn}{\mathrm{Se}}_2$ in near-infrared (NIR) and mid-infrared (MIR) ultrafast photonics are presented. Notably, by employing the $\mathrm{Sn}{\mathrm{Se}}_2$-deposited microfiber device as a saturable absorber (SA) exhibiting typical nonlinear optical absorption properties, stable ultrashort pulses and rogue waves are realized in an erbium-doped fiber laser. Furthermore, the $\mathrm{Sn}{\mathrm{Se}}_2$-deposited SA device is also applied to a thulium-doped fiber laser to achieve stable ultrashort pulses. This study indicates that $\mathrm{Sn}{\mathrm{Se}}_2$ is expected to be a suitable candidate for ultrafast fiber lasers in the NIR and MIR regions.