当前光通信网络正朝着大规模、大容量的方向迅速发展，传输带宽所面临的巨大增长压力对通信光纤提出了更高的要求。在此背景下，基于空分复用的多芯光纤充分利用了空间维度，可以有效解决传统单模光纤的理论传输容量极限导致的容量紧缩问题，而大容量传输系统要求多芯光纤具有低串扰大模场面积的光学特性。通过采用光束传输法和有限元法模拟仿真了多芯光纤中各结构参量对芯间串扰和有效模场面积的影响，并利用两种不同参数的多芯光纤进行了实验验证，对芯间距、纤芯/沟道的尺寸和折射率进行了优化，在理论上完成了串扰小于-45 dB、模场面积大于130 μm2多芯光纤的设计。

Currently, optical communication network is developing rapidly towards large scale and large capacity. Higher request in optical fiber communication system is put forward to face with the huge pressure of transmission bandwidth. Under this background, multicore fiber (MCF) based on space division multiplexing (SDM), overcomes the congestion problem caused by the theoretical transmission limit of single mode fiber. Multicore fiber cannot be used in the transmission system only if it has the optical properties of low crosstalk and large effective area. Intensive simulation work based on beam propagation method (BPM) and finite element method are performed to find out key parameters which have a great influence on crosstalk and effective area in multicore fibers, which are used in the experiment to prove the correctness of simulated results. The designs of core pitch, the size and the refractive index of core and trench are optimized simultaneously to theoretically achieve optical properties suitable for the future large capacity transmission with low crosstalk less than -45 dB after 100 km and large effective areas larger than 130 μm2.