3 kW narrow linewidth high spectral density continuous wave fiber laser based on fiber Bragg grating

Abstract We demonstrated a narrow linewidth monolithic fiber-Bragg-grating-based (FBG-based) MOPA configuration fiber laser with a high power spectral density (PSD). In the oscillator, long-grating-length FBG with narrow reflection bandwidth was employed, combined with a short length resonant cavity, contributing to a narrow linewidth high PSD seed laser. In the amplifier stage, methods were taken to suppress spectrum broadening, such as large-core active fiber and wavelength-stabilized laser diode. As a result, the fiber laser achieved an output power of 3010 W, a spectral 3-dB bandwidth of 103 pm, and a PSD of 29.3 pm/kW. To the best of our knowledge, this is the highest PSD reported by an all-fiber FBG-based fiber laser.