基于复式梯度光子晶体的电磁波的非对称传输

发布时间：2018-06-15 04:06

本文选题：光子晶体 + 非对称传输　；参考：《浙江师范大学》2016年硕士论文

【摘要】：实现电磁波的非对称传输特别是在光波段对集成光路的发展具有潜在的应用价值,因而具有非常重要的研究意义。相比于其他材料,纯介质的光子晶体具有可线性调控、能量损耗低和材料易获得等优点。本文中,我们利用二维纯介质梯度光子晶体实现了光的非对称传输。该体系每个格点包含两根柱子,随着层数的增加对其偏转角引入梯度,可实现电磁波左入射分束而右入射会聚的非对称传输行为。在本文的第一章中,我们首先给出了相关的研究背景,之后介绍了光子晶体的概念、其相关性质和目前的一些应用,最后介绍了本文的基本框架。在第二章中,我们介绍了目前实现电磁波非对称传输的一些方法。利用手性微结构金属阵列和磁性特异介质可以实现电磁波的单向传输。利用能带失配光子晶体做成的异质结实现的电磁波单向传输,以及利用梯度光子晶体实现电磁波分束聚焦非对称传输的相关工作。这些方法或是能量损耗过大,或是传输效率很低,皆不适用与集成光子器件的制作。在第三章中,我们介绍了所使用的数值方法。光子在光子晶体中的行为可以用Maxwell方程组来描述,最终归结为结合边界条件求解亥姆霍兹方程。对于二维圆柱体系,我们用矢量柱波函数作为一组基对场进行展开。我们首先利用Mie散射理论推导出单个散射柱的散射特性,再利用多重散射理论求解出整个体系的散射特性。据此,我们可以获得体系的能带特性、场模式分布以及透射率等。在第四章中,我们给出了一种利用二维介质柱梯度光子晶体实现光的非对称传输的方法。该体系每个格点由两个介质柱构成,两柱子与水平方向的夹角随着层数的增加而呈梯度增加。由于空间反演对称性破缺,高斯光束从左侧入射时分束,从右侧入射时则发生会聚。我们分别从能带和等频线角度分析了非对称现象出现的物理机制。通过对首层偏转角度和梯度的调控,我们发现可以在亚波长尺度实现近场的非对称效应,也可以利用一个较大的体系实现远场的非对称效应,其传输效率皆高于前人的工作。除此之外,同时给半径引入梯度,该体系也可以实现光束的单向传输。在文章的最后,我们对本文的工作进行了回顾和总结,并对基于复式晶格思想开展的后续工作进行了展望。
[Abstract]:The realization of asymmetric transmission of electromagnetic wave, especially in the optical wave band, has potential application value for the development of integrated optical path, so it has very important research significance. Compared with other materials, pure dielectric photonic crystals have the advantages of linear control, low energy loss and easy to obtain materials. In this paper, we use two-dimensional pure dielectric gradient photonic crystal to realize asymmetric transmission of light. Each lattice of the system consists of two columns. The gradient is introduced to the deflection angle with the increase of the number of layers, which can realize the asymmetric transmission behavior of electromagnetic wave beam splitting at left incidence and convergence at right incidence. In the first chapter of this paper, we first give the relevant research background, then we introduce the concept of photonic crystal, its related properties and some current applications. Finally, we introduce the basic framework of this paper. In the second chapter, we introduce some methods of asymmetric electromagnetic wave transmission. The unidirectional transmission of electromagnetic wave can be realized by using chiral microstructural metal array and magnetic specific medium. The unidirectional transmission of electromagnetic wave is realized by using the heterojunction of photonic crystal with band mismatch, and the asymmetric transmission of electromagnetic wave focusing is realized by using gradient photonic crystal. These methods are not suitable for the fabrication of integrated photonic devices either because of excessive energy loss or low transmission efficiency. In chapter 3, we introduce the numerical method used. The behavior of photons in photonic crystals can be described by Maxwell equations, which can be reduced to solving Helmholtz equations with boundary conditions. For two-dimensional cylindrical systems, the vector cylindrical wave function is used as a set of basis for the expansion of the field. We first derive the scattering characteristics of a single scattering cylinder by using Mie scattering theory, and then solve the scattering characteristics of the whole system by using the multiple scattering theory. On this basis, the band characteristics, field mode distribution and transmittance of the system can be obtained. In chapter 4, we present a method for asymmetric transmission of light using two-dimensional dielectric column gradient photonic crystals. Each lattice point of the system is composed of two dielectric columns. The angle between the two columns and the horizontal direction increases with the increase of the number of layers. Due to the symmetry breaking of spatial inversion, the Gao Si beam converges from the left side of the incident time beam, and from the right side of the incident time beam. We analyze the physical mechanism of asymmetric phenomena from the angle of energy band and equal frequency line, respectively. By adjusting the first layer deflection angle and gradient, we find that the near field asymmetric effect can be realized on the sub-wavelength scale, and the far field asymmetric effect can also be realized by using a large system. The transmission efficiency is higher than that of previous works. In addition, a gradient is introduced into the radius, and the system can also realize the one-way propagation of the beam. At the end of the paper, we review and summarize the work of this paper, and look forward to the future work based on the double lattice theory.
【学位授予单位】：浙江师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O734

【相似文献】