Tunable hybrid Brillouin-erbium comb fiber laser in a composite cavity with a single-mode tellurite fiber

We demonstrate a hybrid Brillouin-erbium fiber laser in a composite cavity with a single-mode tellurite fiber. Only a 200 m long tellurite fiber is used in the cavity due to the high effective nonlinearity. The double pass of the tellurite fiber in the linear part is advantageous for improving the Brillouin gain and increasing the comb lines. With a tunable filter, more than 70 comb lines spaced by 7.888 GHz are obtained at 1565 nm. The line number is kept around 60 in the tunable range of 30 nm from 1535 to 1565 nm. Compared with silica fibers, the tellurite fiber can generate a larger number of Brillouin lines in a wider tunable range.