微波波段二维旋磁光子晶体隔离器

发布时间：2018-04-11 00:19

本文选题：旋磁光子晶体 + 磁致能带分裂　；参考：《深圳大学》2017年硕士论文

【摘要】：隔离器一般是一种二端口无源器件,只允许信号单向通过。隔离器在保持信号源的稳定性、减小传输过程中的噪声干扰等方面应用广泛。传统微波隔离器的隔离度一般在20—30dB之间。微波在波导中传输时,存在着类量子霍尔手性边缘态。本文中,我们用COMSOL软件仿真了由磁性光子晶体构成波导边缘时微波的单向传输特性。应用这种单向传输特性,隔离器的隔离度将会提高。在文献[61]结构基础上,我们改进了隔离器结构。改变所加磁场的特性时,隔离器的隔离效果会更好。同时模拟传输还证实了微波在波导中处于手性边缘态时会单向传输,且有障碍物绕射特性。这对于隔离器的设计、制造和使用非常重要。我们运用平面波展开法、时域有限差分法、多重散射法和有限元法等计算和分析了光子晶体的能带结构。在无外加磁场条件下,磁性光子晶体的相邻能带存在着一些简并点;在外加磁场条件下,这些简并点被打破,这是一种磁致能带分裂现象。在这些分裂的能带的边缘,非互易性的传输模式出现,这是手性边缘态出现的根本原因。预先设定光子晶体的晶格常数为1.33厘米,通过对介质柱的半径和波导的宽度的参数扫描,我们确定了隔离器结构的相关参数。最后,我们设计了三种不同结构、工作频率在微波波段的隔离器。二级级联的隔离器的工作频率在14.2—14.8 GHz,最大隔离度能达到30dB;三级级联的隔离器,工作频率在13.7—14.7GHz,它在整个工作频带都具有极高的隔离度,最大时能接近150dB。针对光子晶体系统集成化的发展趋势,我们也初步设计了一种多端口光子晶体隔离器。这在家庭网络中对信号源的分配以及相关互不干扰的应用中,作用重要。
[Abstract]:Isolators are generally two-port passive devices that allow only one-way signal to pass through.Isolators are widely used in maintaining the stability of signal sources and reducing noise interference during transmission.The isolation of traditional microwave isolator is generally between 20-30dB.When the microwave propagates in the waveguide, there is a quantum Hall chiral edge state.In this paper, we use COMSOL software to simulate the unidirectional propagation of microwave when the waveguide edge is composed of magnetic photonic crystals.With this unidirectional transmission feature, the isolation of the isolator will be improved.Based on the [61] structure, we have improved the isolator structure.The isolation effect of the isolator is better when the magnetic field is changed.At the same time, it is proved that the microwave propagates in one direction in chiral edge state and has the characteristic of obstacle diffraction.This is important for the design, manufacture and use of isolators.The band structure of photonic crystals is calculated and analyzed by plane wave expansion method, finite difference time-domain method, multi-scattering method and finite element method.In the absence of an external magnetic field, there are some degenerate points in the adjacent band of the magnetic photonic crystal, and these degenerate points are broken under the condition of the external magnetic field, which is a phenomenon of the splitting of the band.At the edge of these split bands, non-reciprocal transport modes appear, which is the root cause of chiral edge states.The lattice constant of the photonic crystal is 1.33 cm. By scanning the radius of the dielectric column and the width of the waveguide, we determine the relative parameters of the isolator structure.Finally, we designed three different structures, operating frequency in the microwave band isolator.The operating frequency of the two-stage cascade isolator is 14.2-14.8 GHz, the maximum isolation degree can reach 30 dB, and the three-stage cascade isolator has a working frequency of 13.7-14.7 GHz. It has a very high isolation degree in the whole operating band, and the maximum isolation degree is close to 150 dB.In view of the development trend of photonic crystal system integration, we also design a multiport photonic crystal isolator.This plays an important role in the allocation of signal sources and the application of correlation noninterference in home networks.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN62;O734

【参考文献】