磁光效应下二维光子晶体波导的传输属性

发布时间：2018-08-03 14:34

【摘要】：近年来,磁光效应(Magneto Optical,简称:MO)和光子晶体(Photonic Crystal,简称:PC)的组合现象受到越来越多的关注。通常,因为光子晶体的带隙特性,光不可以在晶体中顺利传输,但通过破坏模型结构的完整周期,构造缺陷模式,便可实现光在光子晶体中传输的目的,若再引入磁光材料并对磁光材料施加外部磁场,更会产生有趣的现象。本文主要的研究是针对两个磁表面缺陷模式之间的耦合特性的分析。理论计算上,通过改进一般所使用的平面波展开法(Plane Wave Expansion Method,简称:PWM),得到磁表面缺陷模式以及所构造模型的色散曲线,通过对色散曲线的研究我们获得设计模型的传输属性。完成的工作主要有如下几个方面:1.设计一种新的结构实现光波导开关。在水平方向截断三角晶格二维光子晶体构造出线型波导,并将截断面两侧的原氧化铝柱子替换为磁性材料钇铁石榴石(Yttrium Iron Garnet,简称:YIG),通过对部分YIG介质柱施加同方向的外部磁场,在波导中央形成一道虚拟的“磁反射墙”,禁止光流在该处的传输。去除所施加的外部磁场,则“磁反射墙”消失,光流在波导中顺利传输。实现了光波导开关的功能。2.在光波导开关研究的基础上,选取对全部YIG介质柱施加饱和磁场时出现的特殊凸型曲线深入进行研究。基于凸型曲线所具有的“负折射”效应,实现光自陷和慢光。当光频率处于自陷带中,波导方向没有实质的反射墙,依靠模式本身的属性,光局域在点源附近,而当光处于慢光带中,光流分别在波导的中心线和两侧边界构成驻波和行驻波。3.最后,我们对原先研究的水平单向波导进行改进,仍以YIG作为磁性材料,构造一种新的二维结构的十字波导,该十字波导由水平方向和竖直方向的两个单向波导组成。对于该模型,我们不仅改变了输出端口数量,同时还实现了波导模式的转换,将水平波导中的偶模式部分转化为竖直波导中的奇模式,从而造成了部分奇模式和偶模式在竖直方向波导发生杂化的结果。
[Abstract]:In recent years, more and more attention has been paid to the combination of magneto-optic effect (Magneto Optical,) and photonic crystal (Photonic Crystal,: PC). In general, because of the band gap of photonic crystal, light can not be transmitted smoothly in the crystal, but by destroying the complete period of the model structure and constructing the defect mode, the aim of light transmission in the photonic crystal can be realized. If magneto-optic materials are introduced and external magnetic fields are applied to magneto-optic materials, interesting phenomena will occur. The main research of this paper is to analyze the coupling characteristics between two magnetic surface defect modes. Theoretically, by improving the plane wave expansion method (Plane Wave Expansion Method,: PWM), the magnetic surface defect mode and the dispersion curve of the constructed model are obtained, and the transmission properties of the designed model are obtained by studying the dispersion curve. The work accomplished mainly consists of the following aspects: 1. A new structure is designed to realize the optical waveguide switch. A linear waveguide is constructed by horizontally truncating the two-dimensional photonic crystal of triangular lattice, and the original alumina column on both sides of the truncation plane is replaced by the magnetic material yttrium iron garnet (Yttrium Iron Garnet,). The external magnetic field in the same direction is applied to part of the YIG dielectric column. A virtual "magnetic reflection wall" is formed in the center of the waveguide to prevent the transmission of optical flow there. When the external magnetic field is removed, the "magnetic reflection wall" disappears and the optical flow propagates smoothly in the waveguide. The function of optical waveguide switch is realized. Based on the study of optical waveguide switches, the special convex curves of all YIG dielectric cylinders subjected to saturated magnetic field are studied in depth. Based on the "negative refraction" effect of convex curve, light self-trapping and slow light are realized. When the optical frequency is in the self-trapping band, the waveguide direction has no essential reflection wall. Depending on the properties of the mode itself, the light is localized near the point source, while the light is in the slow band. The optical flow forms standing wave and traveling standing wave at the center line and the boundary of both sides of the waveguide, respectively. Finally, we improve the horizontal unidirectional waveguide studied previously, and still use YIG as magnetic material to construct a new two-dimensional cross waveguide, which is composed of two unidirectional waveguides in the horizontal direction and vertical direction. For this model, we not only change the number of output ports, but also realize the conversion of waveguide mode, which converts the even mode in the horizontal waveguide to the odd mode in the vertical waveguide. This results in the hybrid of partial odd mode and even mode in vertical waveguide.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN252

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