大功率单频多芯光纤放大器中抑制受激布里渊散射的分析

针对多芯光纤完善了描述抽运光、信号光和Stokes信号的速率方程组.考虑了温差对受激布里渊散射的影响，利用有限元法求解温度分布方程组，分析了前向和后向抽运方式、对流系数、Stokes初始功率、光纤掺杂粒子密度和光纤长度对受激布里渊散射增益的影响.研究表明：后向抽运方式在抑制受激布里渊散射方面具有明显优势；减小对流系数有助于抑制受激布里渊散射；提高光纤掺杂密度能够加强抑制受激布里渊散射，同时也有助于提高光纤放大器的斜率效率.比较了在相同最佳光纤长度条件下，单芯和19芯光纤放大器的最高工作温度和受激布里渊散射 关键词： 光纤放大器 受激布里渊散射 大功率 有限元法

Study on the suppression of the stimulated Brillouin scattering in high-power single-frequency multicore fiber amplifier

The set of differential equations for an multicore fiber amplifier with pump, signal and the first-order Stokes, taking into account effects of thermal gradient caused by heat generation, is presented. The thermal conduction equations are solved by finite element method. The influence of pump schemes, pump power, convective coefficient, initial power of Stokes, density of the rare earth dopant and fiber length on suppression of the stimulated Brillouin scattering is studied. The results show that the backward pump scheme has advantage over the forward pump scheme in suppression of stimulated Brillouin scattering. Increasing density of the rare earth dopant can lead to higher slope efficiency and shorter optimal fiber length, which can further suppress stimulated Brillouin scattering. The stimulated Brillouin scattering gain and maximum operating temperature are compared between single core fiber amplifier and 19-core fiber amplifier with the same optimal fiber length. Compared with the single core fiber amplifier, the 19-core fiber amplifier has lower maximum operating temperature, which provides more space for further increase in output power.