Efficient ∼2 μm Tm3+-doped tellurite fiber laser

Laser emission in the range of 1.88-1.99 μm from a Tm3+-doped tellurite fiber is demonstrated when pumped with a diode-pumped Er 3+/Yb3+-doped silica fiber laser operating at 1.57-1.61 μm. This pump source excites the Tm3+ ions directly into the 3F4 upper laser level and yields an output power of 280 mW with a slope efficiency of 76% in a 99%-12% laser cavity arrangement and a 32 cm long fiber. This result is very close to the Stokes efficiency limit of ∼80%. This is, to the authors' knowledge, the first demonstration of high efficiency lasing in a tellurite fiber at wavelengths longer than 1.56 μm.