【作者】 邓新华；

【导师】 刘念华；

【作者基本信息】 南昌大学 ， 材料物理与化学， 2008， 博士

【摘要】 介电常数和磁导率同时或只有一个为负数的新型人工材料是一种具有特殊电磁性质的特异材料,已经在微波段乃至近红外通过人工制备实现。人们通过将特异材料引入到光子晶体中,发现了新型的光子带隙。由于这些光子带隙具有与传统的布拉格带隙截然不同的性质,并具有潜在的应用前景,因此含有特异材料的光子晶体已成为了当前的一个研究热点。本文通过数值模拟和理论分析,研究了含特异材料的光子晶体的光学输运特性。主要的研究内容及其研究成果有以下几个方面:(1)单负材料光子晶体异质结构的频率响应。用带隙不同的两种周期结构构成一维光子晶体异质结构。研究结果表明:当异质结构具有零有效折射率时,在异质结构每一个分界面上都会出现界面模。各界面模的耦合导致光以隧穿的方式传播。在零有效折射率的情况下隧穿模不受入射角、电磁波偏振态、结构周期数等因素影响,并且具有零位相延迟,这一特性可用来设计零位相延迟全向多通道虑波器件;随入射角的增加和单元结构中周期数的增加,位于零有效位相带隙中心的隧穿模频率保持不变,而位于两侧的隧穿模频率向中心移动。(2)基于单负材料光子晶体异质结构的多通道滤波器。研究结果表明:零有效位相带隙内出现的共振模的数目与异质结数M相等,可作为M通道滤波器。当介质存在耗散时,我们得到:结构的异质结数M越大,共振模衰减的幅度越大:耗散因子越大,共振模衰减的幅度也越大。多通道滤波器的品质因子Q值与结构的异质结数M成线性关系,随耗散系数γ的增大而减小。这些为多通道滤波器的品质因子的调节提供了一种可行的方法。(3)负介电常数材料和负磁导率材料交替生长形成的一维光子晶体中的局域共振模。研究结果表明:这种结构的光子晶体具有2个共振隧穿模,并且2个共振隧穿模间距能够通过改变两种单负材料厚度比和缺陷层厚度进行调节。共振隧穿模式场强随着两种单负材料的厚度比的增大而指数增大。随着两种单负材料的厚度比的增大,隧穿模场的局域性也变得更加强烈,电场逐渐向与缺陷层两侧毗连的两个界面集中,两个共振隧穿模的半高宽(FWHM)变窄。此外,这种可调的两个共振隧穿模几乎不随入射角和厚度变化而改变。根据这些特性,我们能够更加实际地利用单负材料制作可调的全向双通道高品质因数滤波器。(4)负磁导率材料和正折射率材料构成的一维周期结构的光子晶体共振隧穿特性。研究结果表明:TE波的传输特性主要取决于ε,TM波的传输特性主要取决于μ.这种由负磁导率材料和正折射率材料构成的一维周期结构的光子晶体在单负带隙内存在一透射带,透射带在TE偏振下对入射角不敏感,而在TM偏振下对入射角敏感。透射带的中心位置取决于正折射率材料层的厚度,而透射带的宽度取决于负磁导率材料层的厚度。透射带的位置和宽度能够通过正折射率材料层和负磁导率材料层的厚度进行独立调节。隧穿模强烈局域在正折射率材料层内,场强幅度随着负磁导率材料层的厚度的增加成指数增大。我们从理论上推导得到了这种结构的光子晶体发生共振隧穿的条件。更多还原

【Abstract】 Metamaterials in which both permittivityεand permeabilityμare negative, or only one of the two parametersεandμis negative, have been realized in microwave and near-infrared. When the metamaterials are introduced into photonic crystals, new types of photonic band gaps appear. Since the properties of such photonic band gaps are different from those of the Bragg gap which leads to potential applications, photonic crystals containing metamaterials have become a hot issue in present research. In this thesis, by means of numerical stimulations and theoretical analysis, we investigate transmission properties of photonic crystals containing metamaterials. The major contents and most important results are given as follows.（1） Frequency response of photonic heterostructures consisting of single-negative materials is studied. We structure heterostructures by useing two photonic crystals with different band gap. The results show that the interface modes emerge on every interface of the heterostructures when the heterostructure is zero effective refractive index. Due to coupling between interface modes, waves can propagate by tunneling. In the case of zero effective refractive index, tunneling mode is independent of incident angles and polarizations and periods and have zero phase delay, which can be utilized to design zero-phase-shift omnidirectional multiple-channeled filters. With the increase of incident angles and period number of unit structure , the frequency of the tunneling mode situated the center of thezero-φ_eff gap is unchanged, while the frequency of the tunneling modes situated bothsides of the center of the zero-φ_eff gap shift to the center.（2） Multiple-channeled filters of photonic heterostructures containing single-negative materials are investigated. The results show that the number oftunneling modes inside the zero-φ_eff gap is equal to the number of heterojunction M, and can be used as M channels filter. When losses are involved, the results show that the electric fields of the tunneling modes decay largerly with the increase of the number of heterojunction and damping factors. Besides, the relation between the quality factor of multiple-channeled filters and the number of heterojunction M is linear, and the quality factor of multiple-channeled filters decreases with the increase of the damping factor, these results provide a feasible method to adjust the quality factor of multiple-channeled filters.（3） We study the local modes of one-dimensional photonic crystals consisting of single-negative permittivity and single-negative permeability media using transfer matrix methods. The results show that there exists a pair of resonant tunneling modes in this structure. The separation of the pair of tunneling modes can be tuned by varying the ratio of thicknesses of the two single-negative layers or the thickness of the defect layer. The electric field intensity of the resonant tunneling modes enhance exponentially with the increase of the ratio of thicknesses of the two single-negative layers. With the increase of the ratio of thicknesses of the two single-negative layers, the electric field of the tunneling modes becomes more localized, and the full width at half maximum of the tunneling modes becomes narrower. Besides, the pair of tunneling modes is insensitive to incident angle and thickness variation. These properties will be used for the design of tunable omnidirectional double-channel filter with high quality factor.（4） Transmission properties studies of one-dimensional photonic crystals consisting of mu-negative and positive index materials are presented by using transfer matrix methods. The results show that transmission properties of TE wavesdepend onε, while transmission properties of TM waves depend onμ, there exists atransmission band inside single-negative gap in this structure, and the transmission band is insensitive to the incident angle for the transverse electric waves but sensitive for the transverse magnetic waves. The position of the center axis of the transmission band is sensitive to the thickness of the positive-index layers, while the width of the transmission band is only dependent on the thickness of the mu-negative material layers. The position and width of the transmission band can be modulated independently by varying the thicknesses of positive index material and mu-negative material layers respectively. The tunneling mode is localized strongly inside positive index material layer, and the electric field enhance exponentially with the increase of the thickness of the mu-negative layers. We derive theoretically analytical expression of the resonant tunneling condition.更多还原