Diode-pumped 1.15 W linearly polarized single-frequency Yb³⁺-doped phosphate fiber laser

Compact and robust high-power single-frequency laser oscillators are in great demand for some specific applications where narrow-linewidth lasers with extremely low noise are required. In this paper, we report a single-mode-diode-pumped watt-level single-frequency Yb³⁺-doped phosphate fiber laser at 1050 nm based on an all-fiber distributed Bragg reflector cavity. A maximum output power of 1.15 W with a slope efficiency of 66% was achieved with 18-mm-long 8 wt.% Yb³⁺-doped phosphate fiber. Stable, single-longitudinal-mode lasing with a spectral linewidth of 9.6 kHz and polarization extinction ratio of ∼30 dB was obtained.