两类单负材料组成的一维半无限光子晶体反射谱

运用传输矩阵方法和Bloch定理计算了两类单负材料组成的一维半无限光子晶体反射谱,与有限多层结构通带中振荡的反射谱相比,半无限结构的反射谱曲线是光滑的,是有限周期结构反射谱振幅取平均的结果,可用来估计通带中的反射率.研究半无限结构的反射谱,有利于分析带隙的位置和宽度,结果表明,由两类单负材料组成的光子晶体中,不仅存在零有效位相带隙,还存在角度带隙,尤其发现高频处的Bragg带隙也是一个全方位带隙.     

含左手材料异质结构光子晶体的零平均折射率带隙的展宽

运用光学传输矩阵理论,研究了含左手材料一维二元光子晶体的禁带特性.提出了含左手材料的光子晶体异质结构中零平均折射率带隙展宽的方法.根据此方法设计的异质结构的光子晶体形成的零平均折射率带隙,与一维光子晶体零平均折射率带隙相比,零平均折射率带隙的宽度和相对带隙宽度可以得到显著的拓宽.而且它的零平均折射率带隙的边缘与TM波和TE波相关.这种特性在微型谐振腔、天线基片、同轴波导等方面都具有潜在的应用.     

引入零平均折射率材料掺杂的一维光子晶体缺陷模的特性研究

本文利用特征矩阵理论模拟了一维光子晶体引入零平均折射率材料的缺陷模特性,发现在基频带隙处出现了孪生缺陷模,并分析了组成零平均折射率材料的正负折射率材料的折射率的变化对孪生缺陷模的位置、透射率和半峰宽度的影响,为双通道窄带滤波器的设计提供了新的思路和理论依据.     

一维含负折射率材料结构中原子的瞬时自发辐射

负折射率材料是一种新型的人工材料，其介电常数和磁导率同时小于零，导致了折射率小于零。当电磁波入射到正负折射率材料的界面上，将会产生负的折射现象。因此单个负折射率材料板能起到能量汇聚的作用。用正负折射率交替排列组成的一维光子晶体能产生不同于通常布拉格带隙的零平均折射率带隙。这种带隙能抑制几乎全方向的辐射，从而能对原子自发辐射产生更强的抑制作用。J．Kastel和M．Fleischhauer最近提出用理想负折射率材料板加上理想反射镜，在适当条件下会完全抑制原子的自发辐射。本文我们考虑在包含实际负折射率材料—有色散和吸收—的一维结构对原子自发辐射的影响。     

半无限一维光子晶体的反射率

本文给出了入射到半无限光子晶体上的波的反射系数计算公式.对由普通材料、双负材料和单负材料组成的一维半无限光子晶体中光的反射进行了数值模拟计算.发现半无限光子晶体的反射率曲线与有限光子晶体相比变得平滑,是有限光子晶体迅速振荡的反射率平均的结果.TE波的反射取决于介电常数的差异,而TM波的反射取决于磁导率的差异.单负-单负材料中的场是倏逝场,存在一个通带使场无位相延迟的传播.当满足eB=-εA,μB=-μA和dA=dB条件时反射率变为零.     

正负折射率材料组成的一维光子晶体的能带及电场

计算了由正负折射率材料交替排列组成的一维光子晶体的能带及电场，发现其能带不同于由普通正折射率材料组成的光子晶体的能带.当选择合适的参数时，由正负折射率材料组成的光子晶体的TE模或TM模有完全光子带隙出现，这在普通光子晶体中不出现.导带中的电场波函数与普通光子晶体相比具有很强的局域性.对于负折射率材料层为色散介质的情况，计算了在不同的具有正负折射率区域能带.     

基于传输线技术的零平均折射率(zero-n-)带隙的实验研究

基于传输线方法,制备了含左手材料和右手材料的一维光子晶体.通过仿真软件ADS的模拟和矢量网络分析仪的测量,研究了光子晶体的传输特性.实验结果表明:由左手材料和右手材料构成的一维光子晶体具有零平均折射率(zero-n-)带隙,这一带隙处于左手通带和右手通带之间.zero-n-带隙分别由零平均介电常量和零平均磁导率决定,进而对晶格尺度不敏感.     

基于传输线技术的零平均折射率(zero-)带隙的实验研究

基于传输线方法,制备了含左手材料和右手材料的一维光子晶体.通过仿真软件ADS的模拟和矢量网络分析仪的测量,研究了光子晶体的传输特性.实验结果表明:由左手材料和右手材料构成的一维光子晶体具有零平均折射率(zero-)带隙,这一带隙处于左手通带和右手通带之间.zero-带隙分别由零平均介电常量和零平均磁导率决定,进而对晶格尺度不敏感.     

平均折射率为零的光子晶体中缺陷模频率特性的实验研究

利用传输线技术制备了左手材料,将左手材料与正常材料交替排列组合成平均折射率为零的一维光子晶体.该光子晶体在特定频段具有光子带隙,带隙不随晶格尺度和入射角的变化而改变.通过掺杂技术破坏光子晶体的周期性,可在禁带中引入缺陷模,这种结构的光子晶体可用于实现滤波器小型化和超强耦合.研究表明,通过调节缺陷的厚度可以控制缺陷模的频率,这为调节频率提供了一种方法.实验与仿真结果相符. 关键词： 左手材料 复合左右手传输线 光子晶体     

含负折射率材料的一维光子晶体禁带特性

运用光学传输矩阵和色散关系理论,研究了由正折射率材料和负折射率材料交替组成的一维光子晶体的禁带特性,发现了一种新型带隙—零平均折射率带隙。与传统的Bragg带隙相比,只要两种介质厚度的比例保持不变,这种零平均折射率带隙的边缘频率,与光子晶体的晶格常数无关,并利用一个等效的传输线模型得出了带隙边缘频率的数学表达式,解释了这个性质。     

负折射率材料对Casimir效应的影响

研究了负折射率材料介质板间的Casimir效应.对于负折射率材料中由Drude-Lorentz型色散关系描述的介电常数和磁导率，色散曲线中负值频带的曲线结构由各色散吸收参数所决定，色散曲线负值频带宽度和负区域的深度等性质的变化影响了介质材料板的反射特性，进而对两材料板间的Casimir效应强弱起着重要的作用.     

Influence of absorption in the zero effective phase gap in one-dimensional photonic crystals containing single-negative materials

The transmission properties of one-dimensional (1D) photonic crystals containing two kinds of single-negative (ENG and MNG) material are investigated theoretically. A type of photonic gap with zero effective phases (zero-φ_eff) and the effects of absorption on the properties of the zero-φ_eff gap were shown. Specifically, it is demonstrated that strong absorption creates photon states inside the gap and this makes the band gap to be of zero width.     

One dimensional photonic band gap material as an omnidirectional reflector

In this article, the reflection properties in one-dimensional dielectric-dielectric photonic band gap (PBG) structure have been studied. We have used SiO₂ as material of low refractive index and Te as a high refractive index material. Reflectivity of proposed PBG structure is plotted as a function of wavelength and angle of incidence and omni-directional PBGs are computed theoretically. To obtain reflectance, we used transfer matrix method for solving Maxwell’s equations for electromagnetic wave in PBG structures. For a large range of frequency, the PBG structure is found to exhibit omni-directional reflection which can be exploited in devices such as optical resonators, mirrors, etc.     

Band-structure properties of photonic superlattices

The band structure of a one-dimensional periodic array composed of two different layers of dimensions a and b characterized by refractive indices n ₁ and n ₂, respectively, is investigated. Refractive indices may take on positive as well as negative values. Within the Maxwell framework and using a transfer matrix technique for one dimensional periodic eigen-problems, we have determined a general equation, which governs the photonic band structure and the density of states (DOS) of one-dimensional photonic crystals. In addition to the well-known existence of the band gaps, we show that, depending on the width relationship b/a between the layer materials, super-lattices with null photonic band gap may exist and the conditions for such occurrences are established. Furthermore, we have been able to study the so-called 〈n〉 = 0 non-Bragg gap, ground ω₀, for which the average refraction felt by the propagating radiation is null. The text was submitted by the authors in English.     

Er$lt;sup$gt;3+$lt;/sup$gt;：YAlO$lt;sub$gt;3$lt;/sub$gt;晶体中Λ型四能级系统的量子相干左手性

用相干量子干涉和电磁感应透明（Electromagnetically induced transparency,EIT） 效应在Er³⁺：YAlO₃晶体中计算得到了Thommen,Mandel和Kastel对原子气提出的Λ型四能级系统的负折射率.计算结果得到的负折射率对应的频带宽度约为1 MHz,比先前报道的10³ Hz量级要宽得多.通常而言对应于折射/吸收比|Re［n］/lm［n］|≈1,而计算所得结果是|Re［n］/lm［n］|为4.6,表明吸收被EIT效应很好地抑制.Im［n］出现的负值可能与Er³⁺的⁴I_13/2→⁴I_15/2跃迁的受激发射有关.由此可知,稀土离子掺杂材料具有丰富的能级和各种不同的电磁跃迁,也是电磁感应负折射率材料中出色的应用材料的候选者. 关键词： 稀土掺杂晶体 量子干涉 电磁感应透明 负折射率材料     

Anomalous lateral beam shift and total absorption due to excitation of surface waves in materials with negative refraction

We studied electromagnetic beam reflection from layered structures that include materials with negative refraction. Excitation of leaky surface waves leads to the formation of anomalous lateral shifts in the reflected beams with single or double peak structures. The presence of reasonable losses within material with negative refraction, besides significant influence on manifestation of the giant lateral shifts, can lead to their total suppression and anomalously high absorption of the incident radiation. If, in addition to the resonant excitation of leaky surface waves, radiation inflow exactly compensates their irreversible damping, total absorption of the incoming radiation can be achieved for moderately wide beams.     

Photonic band gap in the visible range in a three-dimensional solid state lattice

We report on the photonic band gap effect in the visible range in a three-dimensional dielectric lattice formed by closely packed silica spherical clusters and by interconnected cavities filled with various liquids. The spectral position and the spectral width of the optical "stop-band" depend on the lattice period and on the relative sphere/cavity refraction indexn. The stop band peak wavelength shows a linear dependence on n. Transmission characteristics of the lattice have been successfully simulated by numerical calculations within the framework of a quasicrystalline approximation.     

MICROWAVE PROPAGATION IN ROUND GUIDING STRUCTURES BASED ON DOUBLE NEGATIVE METAMATERIALS

This paper presents a theoretical study of guided propagation in a waveguide containing ordinary and negative refractive index (NRI) media. The cut-off frequency of positive/negative combined media is examined. It is calculated for each propagating mode as a solution of a characteristic equation that is solved in terms of Bessel functions, taking into account the implications of the negative refraction. In contrast to what happens in ordinary propagation, mode mixing and crossing and no cut-off modes are found for negative values of ε, μ and refractive index n. The investigation considers the range 1-80 GHz where metamaterials have been demonstrated to work with negative parameters. The results are also compared with the negative core/negative cladding case. Some applications are suggested for devices operating in the microwave frequency domain.     

基于矩形谐振环的新型复合周期结构左手材料研究

通过实验及仿真研究了基于矩形谐振环的新型三角形和三矩形开口谐振环金属线复合周期结构左手材料.仿真研究了以金属铜三角谐振环和三矩形谐振环（SRRs）为基本单元的周期结构负磁导率材料,结果显示两种谐振环均能产生很好的谐振效果,即能产生负磁导率;设计、制作并实验和仿真研究了三角谐振环和三矩形谐振环金属线复合周期结构左手材料,实验结果分别在9.5—13.3GHz和9.8—12.5GHz出现良好的负折射效应,与仿真结果具有较好的一致性.该研究对新型周期结构左手材料的研究、设计和研制具有重要的科学意义和应用前景. 关键词： 左手材料 负折射 三角形谐振环 三矩形谐振环