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 (M(2) approximately 6, 220 microJ) is converted into a near diffraction limited beam (M(2) = 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.
Highlights
High energy pulsed fiber sources open an attractive wide range of applications, such as rangefinding, remote sensing and coherent lidar systems
We propose an original nonlinear beam cleaning fiber laser architecture to obtain high energy pulses with a good beam quality and a narrow linewidth
We proposed and demonstrated a new Stimulated Brillouin scattering (SBS) beam cleanup laser scheme to restore the beam quality after a highly multimode pulsed fiber MOPA at 1.55 μm
Summary
High energy pulsed fiber sources open an attractive wide range of applications, such as rangefinding, remote sensing and coherent lidar systems. Their interest relies on their compactness and robustness thanks to the double-clad diode pumping configuration. Optical damage and nonlinear effects limit the output peak power of standard single mode fibers due to high power density in the fiber core To overcome these limitations Large Mode Area (LMA) fibers are widely used providing more than one kilowatt in continuous-wave [1] or the milijoule level in pulsed operation [2, 3]. The major issue using a narrow-linewidth source is the reduced threshold of Stimulated Brillouin scattering (SBS) in the amplifier chain
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