Brillouin scattering behavior in acoustically guiding single-mode optical fibers with different core diameters

Abstract The Brillouin scattering behaviors in three kinds of acoustically guiding single-mode silica fibers with different core diameters of 8 . 8 μ m , 5 μ m , and 3 μ m were characterized, including the Brillouin scattering spectrum, the stimulated Brillouin scattering (SBS) threshold power, the amount of Brillouin frequency shift (BFS), and the Brillouin linewidth. The experimental results demonstrate that with the same fiber length ( ∼ 10 km), the SBS threshold of the fiber with core diameter of 3 μ m is approximately one sixth of that of standard G652 fiber, which has a core diameter of 8 . 8 μ m . In combination with numerically studies, it is found that small-core fiber with high NA has a distinct advantage in relatively short fiber lengths in terms of reducing SBS threshold. In addition, the amounts of BFS are influenced by both the fiber core diameter and specially the fiber core dopants. Finally, we have also experimentally confirmed that reduced fiber core diameter would lead to the Brillouin linewidth broadening. We believe that these new results provide valuable reference for Brillouin fiber laser.