中文摘要：

随着全光通信的快速发展，波分复用传输系统己不能满足高容量光网络的需求，而模分复用技术利用有限的稳定模式作为独立信道传递信息，可以成倍地提高系统容量和频谱效率，是构建未来光网络的关键技术之一．本文基于掺Bi复合稀土铁石榴石的磁光效应，设计了1．55pm波段的二维三角晶格光子晶体模分复用器．在该光子晶体结构中引入缺陷，形成模式分束波导，通过外加磁场改变其在不同偏振模式下的磁导率，从而控制TE，TM模式的传输，实现了1．55μm波段的模分复用．利用平面波展开法和时域有限差分法对此模分复用器进行了能带和传输特性分析，结果表明：TE和TM模式的透射率均高于92％，信道隔离度分别为19．7dB和42．1dB．这些特性在未来的大容量光传输系统中有着重要的应用前景．

英文摘要：

With the rapid development of all-optical communication, the wavelength division multiplexing transmission system cannot meet the requirements of high capacity in optical networks, while mode division multiplexing uses the limited stability modes as independent channels to transmit information, improving the system capacity and spectrum efficiency, which is one of the key technologies in the construction of future optical network. In this paper, a mode division multiplexer of two-dimensional triangular lattice photonic crystal in 1.55 μm band based on the magneto-optic effect of Bi-doped compound rare earth iron garnet bulk single crystal is proposed. The defects of TbYbBiIG medium are introduced as mode splitting waveguides in photonic crystal, of which the permeability changes with the applied magnetic field in different polarization modes. Therefore, mode division multiplexing in 1.55μm band can be achieved by controlling the propagations of TE and TM mode. The band and transmission characteristics of this device can be analyzed by using the plane wave expansion and finite difference time domain method. The results show that the transmission rates of TE and TM modes both exceed 92% and channel segregation degrees reach 19.7 dB and 42.1 dB respectively. These features indicate the important application prospect in the future high-capacity optical transmission system.