利用耦合模理论对双芯光纤的耦合特性进行了分析,结果表明,双芯光纤的耦合系数与输入信号的波长、光纤直径、2个纤芯间的标准化距离以及光纤的相对折射率差有关,对双芯光纤的参数进行优化可达到最佳效果.在耦合模理论的指导下,提出了一种改进的双芯光纤的制作方法.实验结果表明,该制作方法较原有方法有很大改进. Coupling-mode theory was used to analyze the coupling characteristics of the two-core fiber. The results show that the coupling coefficient of the two-core fiber is related to the wavelength of the input signal, the diameter of the fiber, the normalized distance between two cores and the relative refractive index difference of the fiber, Optimized the parameters of the dual-core fiber to achieve the best results.An improved method of fabricating the dual-core fiber is proposed under the guidance of the coupled-mode theory.The experimental results show that the method has a great improvement over the original method .