Er3+‐doped fiber lasers operating at 2.7 μm have attracted increasing interest because of their various important applications; however, the intrinsic self‐terminating effect of Er3+ and the reliability of glass hosts hindered the development of Er3+‐doped fiber lasers. Herein, the glass‐forming regions of a series TeO2–Ga2O3–R2O (or MO) (R = Li, Na, and Rb; M = Mg, Sr, Ba, Pb, and Zn) glasses are predicted by the thermodynamic calculation method. On this basis, the physical and optical properties of TeO2–Ga2O3–ZnO (TGZ) glass are investigated in detail as an example. Under the excitation of 980 nm laser diode, the fluorescence intensity at 2.7 μm reaches a maximum in the heavily Er3+‐doped TGZ glass. By contrast, the accompanying near‐infrared fluorescence at 1.5 μm and upconversion green emissions at 528 nm and 546 nm are all effectively weaken. Furthermore, the lifetime gap between the 4I11/2 upper laser level and 4I13/2 lower laser level is sharply narrowed from 2.81 ms to 0.59 ms, which is beneficial to overcome the population conversion bottleneck. All results demonstrate that these newly developed ternary tellurite glass systems are promising candidates for near‐/mid‐infrared laser glass fiber, fiber amplifiers, and fiber lasers.

Lasers with a wavelength of 2-μm have important application prospects in those civil and military fields such as laser medical surgery, atmospheric monitoring, remote sensing, due to the strong absorption in water and its eye-safe characteristic 1 . In this research, Ho 3+ ion is a promising candidate for 2 and 2.9 μm lasers owing to the 5 I 7 → 5 I 8 and 5 I 6 → 5 I 7 transitions, respectively. However, it can not be obtained efficiently due to the lack of absorption bands matched with commercial 808 and/or 980 nm laser diodes (LDs). Therefore, sensitized excitation with rare-earth and/or semimetal codoping such as Tm 3+

Fluoro‐sulfo‐phosphate (FPS) glass is of current interest as potential material for laser application due to its good glass‐forming ability, thermal, and chemical stability as well as the complicated local environment for incorporated species. Herein, the physical and luminescent properties of Er3+ and Yb3+/Er3+‐doped FPS glasses vs S/F ratio are investigated comprehensively. The low melting temperature (750°C) leads to fewer ingredients evaporation and easier operation. The sulfate addition depolymerizes the structure of FPS glasses, leading to either monotonic or nonmonotonic variations of physical properties, while no deterioration in thermal and limited one in chemical stability is caused. The addition of sulfate also modifies the local structure around optical active species and thus, leading to higher emission cross section (1.52 × 10−20 cm2), effective linewidth (68.4 nm), figure of merit (5.61 × 10−23 s cm2), gain bandwidth (102.44 × 10−27 cm3), and energy‐transfer microparameters (51.87 × 10−39 cm6/s), implying high possibility to serve as 1.5 μm laser application.

We report a compact all-fiber passively mode-locked ultrafast laser with a fundamental repetition rate of 1.6 GHz that uses a self-developed long-wavelength active fiber, i.e., a fluoro-sulfo-phosphate-based Er3+/Yb3+ co-doped fiber (only 6.2 cm in length). This active fiber can provide a net gain coefficient of 0.6 dB/cm at 1610 nm. The high-repetition-rate all-fiber mode-locked laser operates at a low pump power of only approximately 90 mW. The mode-locked pulse train has a period of 625 ps and a 3 dB bandwidth of 7.0 nm, which can support a transform-limited pulse width of 390 fs.

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