Single-mode thulium-doped silica fiber laser pumped at 1230 nm with 7W of output power

In this paper, we report for the first time efficient single-mode cw operation in 2 mum range of thulium-doped silica fiber laser with core pumping at lambda=1230 nm. We also investigated the possibility of direct pumping from Yb-doped fiber laser without Raman converter (using the short wavelength wing of 1.21 mum absorption band of Tm³⁺ ions). The results obtained demonstrate the possibility of high-power Tm fiber laser pumping with the radiation of the long-wavelength wing of the 1.21 mum transition in the Tm³⁺ ion