972 nm single-frequency distributed Bragg reflector Yb-doped silica fiber laser.

We demonstrated a 972 nm single-frequency distributed Bragg reflector (DBR) Yb-doped fiber laser core-pumped by a watt-level 915 nm Nd-doped fiber laser. A 9 mm long home-fabricated highly Yb-doped silica fiber was used to build the DBR cavity. The direct output power of the 972 nm single frequency fiber laser (SFFL) could reach 42.8 mW when the launched pump power was 800 mW, corresponding to a slope efficiency of 6.1%. The measured linewidth was less than 13 kHz and the optical signal-to-noise ratio exceeded 55 dB. In addition, the laser exhibited an excellent stability, with a power fluctuation of 0.51% and without any instance of mode-hopping during a 2-hours observing. Moreover, benefiting from such a short cavity, this 972 nm SFFL could maintain a single longitudinal mode output in the temperature range of 10-50℃, enabling a wavelength tunability of 276 pm. These features make the laser an excellent seed source for 972 nm high-power, narrow linewidth fiber amplifiers with potential applications in single-photon detection and nonlinear frequency conversion.