Widely wavelength-tunable 2 μm Brillouin fiber laser incorporating a highly germania-doped fiber

We present, for the first time to our knowledge, a wavelength-tunable 2 mu m Brillouin fiber laser based on a homemade thulium-doped fiber laser pump and a segment of highly germania-doped fiber (HGDF). The laser wavelength can be continuously tuned over 110 nm from 1920 to 2030 nm with single frequency operation, and the linewidth is estimated to be less than 0.9 kHz at 1950 nm. Benefiting from the high nonlinearity and low loss of the HGDF, a low lasing threshold of 47 mW is also achieved. (C) 2018 Optical Society of America