基于石英柱模型的光子晶体光纤异常布里渊散射特性的理论研究

通过石英圆柱模型，理论研究了小芯径光子晶体光纤中混合声波模式的色散、模式耦合以及声光相互作用，理论计算出了布里渊散射增益系数谱的双峰结构及其随抽运光波长和温度的演化规律. 理论分析表明光子晶体光纤中布里渊散射增益系数谱的双峰结构源于小芯径光子晶体光纤中混合声波模式之间的模式耦合. 通过温度改变导致的材料参数变化对声波模式色散特性的影响，特别是声波模式耦合点的移动，解释了双峰结构随外界温度的变化规律. 并且，通过理论计算与实验结果的对比讨论了石英圆柱模型的局限性和适用范围. 关键词： 布里渊散射 声光相互作用 模式耦合 光子晶体光纤

Theoretical analysis of novel Brillouin scattering properties in photonic crystal fibers based on silica rod model

Based on an approximate model for acoustic waves in a silica rod with circular cross section, we theoretically investigated the dispersion properties of the hybrid acoustical modes and the acousto-optical interactions in the small core photonic crystal fiber. The calculation result shows that the dual-peaked Brillouin scattering gain coefficient spectrum is caused by the mode coupling of the hybrid acoustical modes in the small fiber core. Together with the dispersion properties of the acoustical modes, the influence of the pump wavelength and temperature on the dual-peaked Brillouin scattering gain coefficient spectrum are also calculated via their influences on the acoustic wave vector and material parameters. Our theoretical results agree with the experimental results well. And we also discuss the limit of application of this model through comparing the theoretical and experimental results.