为了研究基于正方形晶格排列的五芯光子晶体光纤(PCF)的结构参量对耦合特性的影响, 根据其5个超模特征, 给出计算五芯PCF耦合长度的方法, 利用有限元法分析了传输波长以及光纤结构对五芯PCF耦合特性的影响。结果表明, 耦合长度随着传播波长的增加而减小, 随着孔间距、占空比、纤芯折射率以及纤芯直径的增加而增加。该研究为设计基于五芯PCF的定向耦合器提供了理论依据。

To study the influence of the structure parameters of a square five-core photonic crystal fiber (PCF) on coupling characteristics, according to the characteristics of its five super-modes, a method to calculate the coupling length of the PCF was given. The effect of the wavelength and the structure parameters on the coupling characteristics of the PCF was numerically studied in detail with the finite element method. The results show that the coupling length increases with the increase of the core-to-core distance, air-filling ratio, core refractive index and core diameter. However, the coupling length decreases with the increase of the wavelength. The results will provide the theoretical foundations for the design of directional couplers based on five-core PCFs.