Intense 2.71-Μm Fluorescence Emission in Low Hydroxy Heavily Er3+-Doped Fluorotellurite Glass for Mid-Infrared Fiber Laser

Heavily Er3+-doped TeO2–BaF2–La2O3–LaF3 (TBLL) glasses with low hydroxyl absorption (αOH−≈0.025cm−1 ) and high glass transition temperatures (Tg>437℃) were prepared. The Raman spectra and differential scanning calorimetry (DSC) curves were measured to characterize the structural and thermal properties of the glass samples. The emission properties of Er3+-doped TBLL glasses were studied under a 980-nm LD excitation, and the related transition mechanism was discussed. Intense fluorescence emission was noted at 1.55 μm and 2.71 μm, and the intensities of emissions increased monotonically as the doping concentration. Furthermore, the undoped and 6.0 mol% Er3+-doped TBLL bare fibers were prepared. Their chemical durability was tested in deionized water, and the results indicated that the TBLL glass exhibited good antideliquescence ability. Finally, a broad emission band at ~2720 nm was detected in the 6.0-mol% Er3+-doped TBLL bare fiber. These results demonstrate that the novel Er3+-doped TBLL fluorotellurite glass is a candidate for ~3-μm fiber lasers