We demonstrate the generation of a unique regime of multiple solitons in a Tm-doped ultrafast fiber laser at ∼1938.72 nm. The temporal pulse-to-pulse separation among the multiple solitons, 10 in a single-pulse bunch, increases from 0.89 ns to 1.85 ns per round trip. In addition, with the increasing pump power, the number of bunched solitons increases from 3 up to 24 linearly, while the average time separation in the soliton bunch varies irregularly between ∼0.80 and ∼1.52 ns. These results contribute to a more profound comprehension of nonlinear pulse dynamics in ultrafast fiber lasers.

Two-dimensional (2D) tin diselenide (SnSe2), 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, SnSe2 nanosheets have been obtained after pretreatment in an alkaloid, exhibiting high optical absorption and electron-enriched properties. Besides, the performances of the prepared SnSe2 in near-infrared (NIR) and mid-infrared (MIR) ultrafast photonics are presented. Notably, by employing the SnSe2-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 SnSe2-deposited SA device is also applied to a thulium-doped fiber laser to achieve stable ultrashort pulses. This study indicates that SnSe2 is expected to be a suitable candidate for ultrafast fiber lasers in the NIR and MIR regions.

Rogue waves (RWs) are rare, extreme amplitude, localized wave packets, which have received much interest recently in different areas of physics. Fiber lasers with their abundant nonlinear dynamics provide an ideal platform to observe optical RW formation. We review recent research progress on rogue waves in fiber lasers. Basic concepts of RWs and the mechanisms of RW generation in fiber lasers are discussed, along with representative experimental and theoretical results. The measurement methods for RW identification in fiber lasers are presented and analyzed. Finally, prospects for future RW research in fiber lasers are summarized.

We report a regime of the loose soliton bunch in an erbium-doped passively mode-locked fiber laser. In this state, every soliton bunch consists of multiple pulses. The amount of multiple pulses inside the soliton bunch increase as the pump power rises. Moreover, the temporal average pulse-to-pulse separation decreases in general with the increase of the pump power. Further, the spatial-temporal sequences based on the dispersive Fourier transformation technique show that pulse-to-pulse interactions and time jitter can result in pulse forking inside the soliton bunch. Finally, we theoretically demonstrate the soliton bunch with different pulse-to-pulse separations.