Narrow Spectrum Kilowatt-Level MOPA Seeded By Yb-Doped Random Fiber Laser

We proposed and experimentally demonstrated an approach to achieving a narrow spectrum kilowatt-level fiber master oscillator power amplifier (MOPA). The MOPA is seeded by a narrow spectrum random laser with Yb-doped fiber gain and has the spectral broadening-free feature. The narrow spectrum property is sustained during power scaling due to the suppression of nonlinear process. The frequency and time domain of the random laser are well characterized. The proposed one-stage scheme eventually produces 1.105- and 1.073-kW output at 1064 and 1067 nm, and the 3-dB bandwidth are 0.40 and 0.47 nm, corresponding to 0.38- and 0.37-nm random laser seed, respectively. The beam quality of M-2 approximate to 1.4 is achieved at 1.105-kW power level, and the proposed MOPA has the potential of wavelength tunability by simply tuning the fiber Bragg grating of random laser seed.