2.074- $\mu \text{m}$  Lasing From Ho3+-Doped Fluorotellurite Microstructured Fibers Pumped by a 1120-nm Laser
We demonstrate 2.074-μm lasing from Ho<sup>3+</sup>-doped fluorotellurite microstructured fibers (FTMFs) pumped by a 1120-nm Yb<sup>3+</sup>-doped fiber laser. Ho<sup>3+</sup>-doped FTMFs based on TeO<sub>2</sub>-BaF<sub>2</sub>-Y<sub>2</sub>O<sub>3</sub> glasses are fabricated by using a rod-in-tube method. With increasing the pump power to 253 mW, lasing at 2.074 μm is achieved from a 42-cm-long Ho<sup>3+</sup>-doped FTMF. With further increasing the pump power to 1015 mW, a maximum unsaturated power of 98 mW is obtained, and the corresponding slope efficiency is up to 12.4%. In addition, relatively strong 1.2- and 2.9-μm emissions are also observed from the Ho<sup>3+</sup>-doped FTMF.