2.4  kW 1045  nm narrow-spectral-width monolithic single-mode CW fiber laser by using an FBG-based MOPA configuration

A 24 kW narrow-spectral-width near-diffraction-limited monolithic fiber laser system at ${\sim}{1045.2}\;{\rm{nm}}$ in a fiber Bragg grating (FBG)-based master oscillator power amplifier (MOPA) configuration is demonstrated in this paper. The near-diffraction-limited beam quality (${{\rm{M}}^2}\sim{1.2}$) and a spectral width of 0.35 nm (${\sim}{{96}}\;{\rm{GHz}}$) are achieved. The stimulated Raman scattering (SRS) is theoretically and experimentally investigated. The SRS has been suppressed by carefully optimizing the length of the Yb-doped fiber and the pumping scheme, and a signal-to-noise ratio of ${\sim}{{33}}\;{\rm{dB}}$ between the laser signal and the Raman Stokes component is achieved. The stimulate Brillouin scattering and the transverse mode instability are not observed. To our best knowledge, this is the highest-output power for ${{104}} \times {\rm{nm}}$ single-mode fiber laser with ${\sim}{{96}}\;{\rm{GHz}}$ spectral width by using an FBG-based MOPA configuration.