All-fiberized linearly polarized superfluorescent fiber source with 5  kW power output

A superfluorescent fiber source (SFS) is a special fiber source that commonly possesses high temporal stability and a wide spectral linewidth. In this work, an all-fiberized linearly polarized SFS with, to our knowledge, record output power and near-diffraction-limited beam quality is presented. Up to 5.03 kW SFS is achieved at a pump power of 6.18 kW with a corresponding conversion efficiency of ∼81.1%. At maximum output power, the signal-to-noise ratio to background spectral noise is over 50 dB, the polarization extinction ratio is ∼17d B, and the beam quality factor is M _x ²=1.49, M _y ²=1.44. Further comparisons confirm the power scalability of fiber amplifiers employing SFSs as seed lasers. Overall, this work could provide a good reference for potential exploration of high-power fiber laser systems.