High energy, single-mode, narrow-linewidth fiber laser source using stimulated Brillouin scattering beam cleanup

Abstract : We propose an original nonlinear beam cleaning fiber laser architecture to obtain high energy pulses with a good beam quality and a narrow linewidth. The output beam of a large core Er:Yb co-doped multimode fiber amplifier (M2 ~ 6, 220 μJ) is converted into a near diffraction limited beam (M2 = 1.6) through a stimulated Brillouin scattering injection seeded beam cleanup process. We report in this experiment a multimode to single mode conversion efficiency of 50% while preserving the master oscillator linewidth