Watt-level ∼2μm laser output in Tm^3+-doped tungsten tellurite glass double-cladding fiber

We report, for the first time to the best of our knowledge, a watt level cw fiber laser at ∼2μm from a piece of 40-cm-long newly developed highly thulium-doped (3.76×1020ions/cm3) tungsten tellurite glass double cladding fiber pumped by a commercial 800nm laser diode. The maximum output power of the fiber laser reaches 1.12W. The slope efficiency and the optical–optical efficiency with respect to the absorbed pump are 20% and 16%, respectively. The lasing threshold is 1.46W, and the lasing wavelength is centered at 1937nm.