Over 100 mW linearly polarized single-frequency fiber laser based on Er:YAG crystal-derived silica fiber

The realization of single-frequency fiber lasers requires high-gain media. In this work, an Er:YAG crystal-derived silica fiber (EYDSF) was prepared using the melt-in-tube method, whose gain coefficient was up to 2.11 dB/cm using a pump power of 1480 nm. A linearly polarized single-frequency fiber laser was constructed based on a 2-cm-long EYDSF. The optical-to-optical conversion efficiency was 27.0%. A fiber mirror was used at the end of the cavity to reflect the residual pump, which can be absorbed by the EYDSF to further increase the output power. The maximum output power and the slope efficiency of the proposed laser were over 100 mW and up to 22.4%, respectively. To the best of our knowledge, it has the highest output power and the largest slope efficiency, compared with the previous single-frequency fiber lasers based on EYDSFs. In addition, the laser had good polarization and noise performance with a polarization extinction ratio of 25 dB and a relative intensity noise of <- 139 dB/Hz. The performance of the proposed fiber laser demonstrates its great potential as a seed source for coherent optical communications, laser combining systems, and other fields.