In recent years, mid-infrared (mid-IR) lasers have attracted a great interest over the world. During the development of mid-IR laser sources, the 2 μm Tm3+-doped fiber laser (TDFL) has played an important role for its specific emission wavelength between near-IR and mid-IR. Its great potential applications include sensing, medical surgery, ranging, telecommunications, and pump sources for developing 3–5 μm laser systems. Though the continuous-wave (CW) output power of 2 μm TDFLs has been scaled to over 1000 W, high-pulse-energy ultrafast 2 μm TDFLs are still limited by nonlinear optical effects. In traditional soliton mode-locking, the pulse energy has an upper limit defined by the soliton area theorem (or energy quantization principle). For improving the pulse energy of 2 μm fiber lasers, dissipative soliton (DS) mode-locking may be one of the efficient solutions. In this chapter, the current state of the art in high-energy ultrafast DS 2 μm TDFLs developed in our laboratory is reviewed, and the potential and prospect of this theme are analyzed. By introducing a new model, condensed-gain fiber mode-locking, we show that the soliton pulse energy of 2 μm TDFLs can be steadily scaled to over 10 nJ and various soliton dynamics (harmonic mode-locking, soliton molecules, etc.) can be observed. Furthermore, DS mode-locking of TDFLs with one of the two-dimension-like materials (MoS2) is investigated.
Part of the book: High Power Laser Systems