Solid state laser sources operating in the eye-safe ~2 µm spectral region have attracted a great deal of interests due to their applications in laser remote sensing, medicine, atmospheric monitoring, and eye-safe lidar. Tellurite (TeO₂) glass possesses some important advantages over other common fiber glass hosts. It is an ideal laser medium for achieving ~2 μm fiber laser. Until now the published highest power of a Tm³⁺-doped tellurite fiber laser at ~2 μm was 280 mW, with  a 1.57–1.61 μm Er³⁺/Yb³⁺-doped silica fiber laser as pumping source.

　　The high power laser components R&D center at Shanghai Institute of Optics and Fine Mechanics (SIOM/China), led by Prof.Lili Hu, has recently achieved a breakthrough in ~2 μm glass fiber laser. Researchers in this laboratory demonstrated for the first time a watt level cw fiber laser at ~2 μm from a piece of 40 cm long highly thulium-doped (3.76×10²⁰ions/cm³Tm³⁺ion concentration) tungsten tellurite glass double cladding fiber. It was one end pumped by a commercial 800 nm laser diode. The maximum output power of the fiber laser reaches 1.12 W. This is the highest ~2 μm laser output power in thulium-doped tellurite fiber. The lasing threshold was 1.46 W. The slope efficiency and the optical-optical efficiency with respect to the absorbed power were 20% and 16%, respectively. The lasing wavelength was centered at 1937 nm, and the full width at half maximum (FWHM) of the lasing spectrum was ~15 nm.

　　This low lose (<2.9 dB/m @1310nm) double cladding fiber made from a novel tungsten tellurite glass with high glass transition temprature (Tg>450 ℃) and low coefficient of thermal expansion (CTE<125×10^-7/℃), was newly developed by Kefeng Li and Guang Zhang, PhD students of the high power laser components R&D center in SIOM. 

　　Present results extend the knowledge of laser glass family, and offer the prospects of making possible new fiber devices based on the novel tungsten tellurite glass.

　　This research is supported by the State High-Tech development plan numbered 2007AA03Z441 and the CAS/SAFEA International Partnership Program for Creative Research Teams.