Lasing at 2.72 µm in an Er-doped high-purity tungsten-tellurite glass fiber laser.

This Letter reports the experimental realization, for the first time to our knowledge, of lasing in an erbium-doped tellurite fiber at 2.72 µm. The key to the successful implementation was the use of advanced technology for obtaining ultra-dry preforms of tellurite glasses, as well as the creation of single-mode Er-doped tungsten-tellurite fibers with an almost imperceptible absorption band of hydroxyl groups, with a maximum of ∼3 µm.