Stimulated Brillouin threshold reduction by core microstructuration in multifilament core fibers

High power fiber amplifiers producing long pulses (> 50ns) with narrow linewidth (< 1MHz) have many applications in remote sensing and Lidar systems. In this regime, the output power is usually limited by stimulated Brillouin scattering (SBS). We have recently demonstrated erbium-ytterbium doped multifilament core (MFC) fibers for amplification of narrow linewidth pulses with high (> 1 kW) SBS threshold and M²~1.3. In this new fiber structure, the core is composed of 37 erbium-ytterbium filaments surrounded by fluorine doped silica.