外磁场调制下一维磁性光子晶体的传输属性

发布时间：2018-04-23 01:23

本文选题：磁性光子晶体 + 空间反演对称　；参考：《江苏大学》2017年硕士论文

【摘要】：磁光效应与磁性光子晶体的结合是光子晶体研究领域一个新的热点。磁性光子晶体在外磁场的作用下,磁导率为张量形式并且非对角元素为虚数,系统的时间反演对称性发生破缺,从而实现电磁波的单向传输。另外这些元素会随着外加偏置磁场强度的变化而变化,进而使得光子晶体的能带结构发生改变,实现可调谐的特性。本论文针对磁性光子晶体的特点,利用基于磁性光子晶体的传输矩阵法,对一维磁性光子晶体的传输属性进行了研究,并设计出不同功能的光子器件。本文首先设计了四种周期性结构的一维光子晶体,利用空气层作为缺陷,分别计算其透射谱,通过比较验证了只有当系统的时间反演对称性和空间反演对称性同时破缺时,才可实现非互易传输,并且这种对称性破缺程度越高,透射谱的分离度越大。紧接着在此基础上继续研究了缺陷层厚度和入射角度对非互易传输的影响,发现通过调节缺陷层厚度和入射角度,非互易传输会形成高透射率和大消光比,该结构可以被用作光学隔离器等非互易器件。另外,在此基础上本文提出了一种新的机制实现单向传输,一维磁性光子晶体的透射率可以通过传输矩阵的方法计算,仿真可以采用有限元的方法。通过两个非平行磁性光子晶体的串联,正向透射谱可以被裁剪成一个单峰,反向透射谱形成一个宽的禁带,一个完整的单向传输就发生在宽的禁带背景内,这是本文一个创新点。随后本文提出了一种由负介电常数材料和磁性材料(YIG)周期性排列组成的磁微腔系统,通过耦合腔谐振器的光子隧穿效应设计了一个多通道滤波器,利用紧束缚模型和传输矩阵方法,分析其传输机制并研究其传输特性。通过微腔的耦合,单个谐振模式分裂成一些离散的单峰,从而形成多通道滤波。同时我们也分析了入射角度和负介电常数材料薄膜的厚度对滤波特性的影响,研究发现合适的结构参数能使滤波器性能达到最优。结合磁性材料的可调谐特性,我们进一步改变外加偏置磁场的强度,发现随着外加偏置磁场的强度变化,滤波通道会出现移动,从而实现通过改变磁场强度控制滤波器通道位置的功能。
[Abstract]:The combination of magneto-optic effect and magnetic photonic crystal is a new hotspot in the field of photonic crystal research. Under the action of external magnetic field of magnetic photonic crystal, the permeability is Zhang Liang form and non-diagonal element is imaginary number, the time inversion symmetry of the system is broken, thus the one-way transmission of electromagnetic wave is realized. In addition, these elements will change with the intensity of the applied bias magnetic field, and the band structure of the photonic crystal will be changed to achieve the tunable characteristics. According to the characteristics of magnetic photonic crystals, the transmission properties of one-dimensional magnetic photonic crystals are studied by using the transfer matrix method based on magnetic photonic crystals in this paper, and photonic devices with different functions are designed. In this paper, four kinds of periodic one-dimensional photonic crystals are designed and their transmission spectra are calculated by using the air layer as the defect. It is verified by comparison that only when the time inversion symmetry and the spatial inversion symmetry of the system break at the same time. The higher the degree of symmetry breaking, the greater the degree of separation of transmission spectrum. Then, the influence of defect layer thickness and incident angle on non-reciprocal transmission is studied. It is found that by adjusting the defect layer thickness and incident angle, the non-reciprocal transmission will form a high transmittance and a large extinction ratio. The structure can be used as non-reciprocal devices such as optical isolators. In addition, a new mechanism is proposed to realize unidirectional transmission. The transmissivity of one-dimensional magnetic photonic crystal can be calculated by the method of transmission matrix, and the finite element method can be used in simulation. Through the series of two nonparallel magnetic photonic crystals, the forward transmission spectrum can be cut into a single peak, and the reverse transmission spectrum forms a wide band gap, and a complete one-way transmission occurs in the wide forbidden band background. This is an innovation in this paper. Then a magnetic microcavity system consisting of negative dielectric constant materials and magnetic materials is proposed. A multichannel filter is designed by the photon tunneling effect of the coupled cavity resonator. The transmission mechanism is analyzed and its transmission characteristics are studied by using the tight-binding model and the transmission matrix method. By coupling the microcavity, the single resonant mode is split into some discrete single peaks, thus forming multi-channel filtering. At the same time, we analyze the influence of incident angle and thickness of negative dielectric constant material film on the filter characteristics. It is found that proper structure parameters can make the filter performance optimal. Combined with the tunable properties of magnetic materials, we further change the intensity of the applied bias magnetic field. It is found that the filter channel will move with the change of the intensity of the external bias magnetic field. Thus, the function of changing the magnetic field intensity to control the position of the filter channel is realized.
【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】：O734;TN713

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