Recent progress on power scaling and single-frequency operation of 1.7-μm thulium-doped fiber lasers

•The principle and recent efforts on efficient short-wavelength operation of Tm3+-doped fiber lasers at 1.7 μm have been introduced.•Key factors and main obstructions towards achieving high-power 1.7 μm Tm3+-doped fiber lasers have been analyzed.•Recently developed techniques of linewidth narrowing to achieve single-frequency 1.7 μm laser operation have been summarized and discussed.