LAUSR

The purpose of this paper was to develop fiber lasers in the 2.7–2.8 μm range based on the tungsten–tellurite glass fiber that is technically robust compared to the other fibers currently used in laser engineering. Using an advanced technology for producing ultra-dry tellurite glasses, we manufactured Er3+-doped tungsten–tellurite glass preforms with extremely low absorption and obtained active single-mode tungsten–tellurite fibers. Based on a 70 cm long fiber, we developed a laser oscillator pumped by a low-cost, high-efficiency diode laser at 976 nm. At the highest used pump power, the laser output reached 33 mW, which may be interesting for practical applications. We also measured the single-pass on/off gain of the fibers and showed that with increasing pump power amplification, as high as 5 can be reached, showing that such active fibers may also be used for increasing laser output.