Influence of the polarization and optical axis on the transmission behavior in a one dimensional photonic crystal containing uniaxial metamaterial

In this letter, we introduce a one-dimensional photonic crystal (1DPC) structure with a uniaxial metamaterial defect layer. It is proposed to control the transmitted wave of the defect mode by adjusting the orientation of the optical axis and incidence angle for both polarization states. The 4 × 4 transfer matrix method was employed to calculate the transmittance spectrum of the proposed structure. It is shown that the photonic band gaps, the intensity and the peak wavelength of the defect mode depends on the polarization, the orientation of the optical axis and the incidence angle of the wave, due to the strong anisotropy of the metamaterial. The transmittance spectrum curves at different optical axes of the uniaxial metamaterial and the distinct incidence angles are illustrated graphically. It is shown that the defect mode appears as a peak in the transmission spectrum. Pronounced contrasts in the intensity, wavelength positions of the defect mode and photonic band gap were demonstrated depending on the incidence angle and the orientation of the optical axis of the uniaxial metamaterial defect layer for both polarizations. Our structure offers a great variety of possibilities for designing and controlling the transmitted intensity of the defect mode.     

Near-infrared tunable narrow filter properties in a 1D photonic crystal containing semiconductor metamaterial photonic quantum-well defect

The near-infrared (NIR) narrow filter properties in the transmission spectra of a one-dimensional photonic crystal doped with semiconductor metamaterial photonic quantum-well defect (PQW) were theoretically studied. The behavior of the defect mode as a function of the stack number of the PQW defect structure, the filling factor of semiconductor metamaterial layer, the polarization and the angle of incidence were investigated for Al-doped ZnO (AZO) and ZnO as the semiconductor metamaterial layer. It is found that the frequency of the defect mode can be tuned by variation of the period of the defect structure, polarization, incidence angle, and the filling factor of the semiconductor metamaterial layer. It is also shown that the number of the defect mode is independent of the period of the PQW defect structure and is in sharp contrast with the case where a common dielectric or metamaterial defect are used. The results also show that for both polarizations the defect mode is red-shifted as the number of the defect period and filling factor increase. An opposite trend is observed as the angle of incidence increases. The proposed structure could provide useful information for designing new types of tuneable narrowband filters at NIR region.     

用两端对称缺陷复合光子晶体实现多通道滤波和光开关

用传输矩阵法计算了两端对称缺陷复合光子晶体结构的光传输特性。计算结果表明:两端对称缺陷复合光子晶体[D(AB)mD]2结构中的禁带出现两个完全共振透射峰。通过控制入射光强来微调光子晶体材料的介电常数,使得完全共振透射峰移动,且介电常数变化越大,共振透射峰偏移越大,从而形成高效率的双通道光开关。当光子晶体为[D(AB)mD]N结构时,每个完全共振透射峰都分裂为N-1条,这样可通过调节N同时实现所需要通道数目的高效多通道光开关和多通道滤波器。     

Low-dimensional waveguide microwave photonic crystals

Structures containing periodically alternating elements, which are a source of high-order waves, are investigated as low-dimensional waveguide microwave photonic crystals. The band character of the transmittance and the reflectance of a photonic crystal, which consists of sequentially alternating dielectric layers and thin metallic plates partially overlapping the waveguide section, is revealed by the numerical modeling and the experimental investigation of amplitude-frequency characteristics. It has been shown that the application of metallic plates with gaps in the structure of the photonic crystal made it possible to decrease its longitudinal size substantially compared with photonic crystals fabricated based on elements made of alternating dielectric layers with various permittivities.     

One-dimensional photonic crystals with a planar oriented nematic layer: Temperature and angular dependence of the spectra of defect modes

Transmission spectra of a one-dimensional photonic crystal (PC) formed by two multilayer dielectric mirrors and a planar oriented layer of 5CB nematic liquid crystal (LC) that is sandwiched between these mirrors and serves as a structure defect are investigated experimentally. Specific features of the behavior of the spectrum of defect modes as a function of the angle of incidence of light on the crystal are studied for two polarizations: parallel and perpendicular to the director of the LC; the director either lies in the plane of incidence or is perpendicular to it. It is shown that, for the configurations considered, the maxima of the defect modes shift toward the short-wavelength region as the tilt angle of incidence radiation increases; this tendency is more manifest for the parallel-polarized component, when the director lies in the plane of incidence. In the latter case, the width of the photonic band gap (PBG) appreciably decreases. The temperature dependence of the polarization components of the transmission spectra of a PC is investigated in the case of normal incidence of light. The spectral shift of defect modes due to the variation of the refractive index of the LC at the nematic-isotropic liquid phase transition point is measured. It is shown that, in real PCs, the amplitude of defect modes decreases when approaching the center of the band gap, as well as when the number of layers in the dielectric mirrors increases. Theoretical transmission spectra of the PCs calculated by the method of recurrence relations with regard to the decay of defect modes are in good agreement with experimental data.     

Design of Narrowband Optical Filters Using Binary Number Sequence Photonic Crystals

A theory to design narrow band optical filters by using a new photonic crystal structure is presented. This new photonic crystal structure is composed of low index layers and high index layers arranged in mod. 4 up and down binary number sequence. The new structure exhibits narrow transmission peaks in the forbidden frequency gap region with high optical transmission (greater than 99.98%) at C.W.D.M. (Coarse Wavelength Division Multiplexing) center wavelengths. The proposed filters use only 8 layers. These new binary number sequence photonic crystal narrowband optical filters are much smaller in size, lower in cost and easier to fabricate as compared to narrowband photonic crystal optical filters based on defect Fractal Cantor multilayers, suggested recently by a group of researchers.     

Fabrication of near infrared metallodielectric photonic crystal using metal-coated dielectric spheres

A metallodielectric photonic crystal with photonic band gaps in near infrared regime has been constructed using layer-by-layer stacking of two-dimensional micro-size metal-coated dielectric spheres array. In transmission spectra two photonic band gaps are observed at 1.38 μm and 2.46 μm, which are in agreement with theoretical calculations. Experimental results show that the photonic band gaps can be realized with about ten layers. The structure with metallic microspheres provides us a novel way for fabrication of near infrared metallic photonic crystals.     

可见光波段SiO2/CdSe一维光子晶体及缺陷模的研究究

采用SiO2/CdSe构建了可见光波段一维光子晶体结构,并在其中引入LiTaO3缺陷层。利用传输矩阵法,分析了电磁波在无缺陷与含LiTaO3缺陷层两种光子晶体中的带隙结构,系统地研究了缺陷层参数对光子晶体可见光波段带隙结构的影响规律。计算结果表明：LiTaO3的引入,有利于带隙宽度的增加,调整缺陷层结构参数,缺陷模的位置可在不同颜色区域出现,如红光、黄光等缺陷模。该结构有望用于制作可见光波段的滤波器。     

用一维光子带隙结构增强硫化镉双光子吸收研究

用真空镀膜方法制备了含有单个CdS缺陷层的具有不同周期和结构参量的TiO2／SiO2一维光子晶体。用抽运一探测技术研究了CdS缺陷层的双光子吸收（TPA）现象。实验结果表明：一维光子晶体中CdS缺陷层的双光子吸收显著增强。不同周期和结构参量的一维光子晶体中CdS缺陷层的双光子吸收系数不同。双光子吸收的增强来源于由光局域化导致的缺陷层的电场强度的增加。缺陷层电场强度与一维光子晶体的结构有关,如周期,光子带隙的位置与宽度及缺陷模式等因素都会影响缺陷层电场强度。采用四分之一波长的高低折射率介质层和与入射波长匹配的缺陷模可以得到最大的缺陷层电场强度。     

色散负折射特异介质的1维光子晶体缺陷态

在1维光子晶体中引入色散负折射特异介质,分析了其介电常数和磁导率在微波区（1～10 GHz）与频率的关系。分别对以色散负折射介质为缺陷的正折射率介质光子晶体及以正折射率介质为缺陷的正负折射率介质光子晶体进行了数值仿真,得出了均匀平面电磁波在正入射和斜入射时的透射谱。结果表明:在介电常数和磁导率均为负值的不同禁带中,分别出现了单、双缺陷模。利用透射谱的这一特点,可实现单、双通道滤波。     

Broad Stopband Characteristic of Dielectric Chiral Photonic Crystals

In this paper, a novel chiral photonic crystal structure is presented. The formula of reflection coefficient of multi-layer chiral media is applied to dielectric-chiral photonic crystal structure, which is composed of thin chiral layers sandwiched by conventional media. To compare with previous literature, we consider the dielectric structure with alternate glass and GaAs layers. The power reflectance as a function of wavelength for this photonic crystal structure has been calculated. The results are in good agreement with that of Reference. However, our method is simpler. From these graphs, it is found that 100% reflectance is only in finite wavelength ranges, and reflection bandwidth is also small for conventional photonic crystal structure. For chiral photonic crystal, the results show that the chiral photonic band gap (PBG) structure gives nearly 100% reflections in the near-infrared region in addition to some parts of the visible region of the wavelengths. Therefore, it can be used as a broadband reflector and filter.     

多系双局域态光子晶体的可调谐滤波特性分析

利用紧束缚方法分析了双局域态光子晶体产生双缺陷模的机理, 采用传输矩阵法研究了一维光子晶体的光学传输特性, 并得到了透射谱与晶体结构参数的关系, 在此基础上讨论了光子晶体在受到单轴应力时所表现出的介观压光效应, 据此设计了一种结构简单的应力调制的近红外波段的多通道滤波结构.通过数值模拟可以看出, 随着各介质层折射率或厚度的增加, 缺陷模发生红移.当对多系双局域态光子晶体施加单轴拉伸应力时, 各缺陷峰都向长波长移动, 且缺陷峰峰值基本不变.经过数值拟合, 缺陷峰中心波长与对光子晶体施加单轴拉伸应力所产生的应变呈线性关系.该滤波器结构简单、可调谐性好, 在一系列精巧的光子晶体激光器、波分复用器或者其他精密仪器的制造中有一定的应用价值.     

Investigation of defect modes in a defective photonic crystal with a semiconductor metamaterial defect

In this work, we theoretically investigate the properties of defect modes in a defective photonic crystal containing a semiconductor metamaterial defect. We consider the structure, (LH)^N/D^P/(LH)^N, where N and P are respectively the stack numbers, L is SiO₂, H is InP, and defect layer D is a semiconductor metamaterial composed of Al-doped ZnO (AZO) and ZnO. It is found that, within the photonic band gap, the number of defect modes (transmission peaks) will decrease as the defect thickness increases, in sharp contrast to the case of using usual dielectric defect. The peak height and position can be changed by the variation in the thickness of defect layer. In the angle-dependent defect mode, its position is shown to be blue-shifted as the angle of incidence increases for both TE and TM waves. The analysis of defect mode provides useful information for the design of tunable transmission filter in semiconductor optoelectronics.     

On transmittance and localization of the electromagnetic wave in two-dimensional graphene-based photonic crystals

Two-dimensional graphene-based photonic crystal (GPC) formed by a periodic array of the homogeneous dielectric cylinders etched in the alternating graphene and dielectric layers and its inverse counterpart are considered. The transmittance of the photonic crystal is obtained. The waveguide due to the localization of the electromagnetic wave on the lattice defect that breaks the translational symmetry of the GPC of two different topologies is studied. The different topologies of GPC are characterized by different photonic band structures with different widths of photonic band gaps (PBG) and provide different frequencies for the localized electromagnetic wave due to the defect. The frequencies of the localized mode for both type of the GPC, located inside the lowest PBG, are in the range of THz or tens of THz depending on the topology of the GPC. It is shown that the photonic band gap always can be tuned by changing the chemical potential of graphene to provide formation of the localized photonic mode due to the defect. The technological advantages of the GPC, as well as the opportunity to tune the PBG and the frequency of the localized electromagnetic wave in the terahertz region of spectrum for the GPC are discussed.     

一维光子晶体带隙结构研究

在考虑介质色散的基础上,研究了介质层厚度对光子晶体带隙结构的影响.利用传输矩阵法,计算了以LiF和Si两种材料组成的一维光子晶体带隙结构.结果表明,介质层厚度的增加会引起禁带的红移,厚度减小会引起蓝移.分析了含空气缺陷层、金属缺陷层的光子晶体结构,发现空气缺陷层对带隙结构的高反射区域变化不大,而在低反射区域,反射系数为零的波带之间出现了两边反射系数增加,中间反射系数减小的情况.在金属缺陷层的带隙结构中,金属对整个波长范围光的吸收作用不同,金属对低反射区1.6 μm、1.85 μm处透射率较大的透射光吸收作用明显,而在1.28~1.38 μm处透射率波长区间,几乎无吸收.     

含超导材料Thue-Morse序列一维光子晶体传输特性研究

超导光子晶体是一类重要的带隙可调谐的光子晶体.利用传输矩阵法研究了含超导材料的Thue -Morse序列准周期结构—维光子晶体在可见光波段的传输特性.数值结果表明在正入射时,光子带隙宽度和位置基本不随序列项数的增加而改变;准周期超导光子晶体的传输特性可以通过改变传统电介质材料的结构参数和环境温度等来进行调节.     

带缺陷二维光子晶体的透射谱研究

在一维线缺陷的研究基础上进一步应用转移矩阵方法数值研究带其它缺陷的二维正方晶格圆柱光子晶体的透射谱,缺陷的引入使得原来不透电磁波的禁带中,出现了缺陷模,即某一波长的电磁波可以透过,计算结果表明禁带位置、宽度,缺陷模的位置与透过率随着缺陷的种类、介质、程度有关,特别是都受到波源的入射角调制.     

基于像素法用模拟退火-遗传算法搜索一维宽带隙光子晶体

将一维光子晶体用像素填充法进行二进制编码,把模拟退火、遗传算法、模拟退火-遗传混合算法与传输矩阵法结合,搜索、计算了一维光子晶体结构和能带,找到了全方位相对禁带宽度高达43.53%的四层结构和43.76%的两层结构,并给出了一维四层结构光子晶体的能带图及其4个原胞的反射率和透射率的频谱图;发现一维两层结构光子晶体的全方位禁带宽度对每层厚度的变化不敏感,但随着两种介质折射率差的增加而增大.     

Graphene-based one-dimensional photonic crystal

A novel type of one-dimensional (1D) photonic crystal formed by an array of periodically located stacks of alternating graphene and dielectric stripes embedded into a background dielectric medium is proposed. The wave equation for the electromagnetic wave propagating in such a structure is solved in the framework of the Kronig-Penney model. The frequency band structure of the 1D graphene-based photonic crystal is obtained analytically as a function of the filling factor and the thickness of the dielectric between the graphene stripes. The photonic frequency corresponding to the electromagnetic wave localized by a defect of the photonic crystal formed by an extra dielectric placed in the position of one stack of alternating graphene and dielectric stripes is obtained.     

Graphene based photonic crystal optical filter: Design and exploration of the tunability

Optical characteristics of two new graphene based photonic crystals are studied in detail. A structure containing alternating layers of graphene and SiO₂ slabs is considered as the ideal crystal. The dependency of the photonic band gaps (PBGs) to the dielectric layer thickness and the period number is explored at first step. Potential of the proposed crystal to be used as an optical filter is then investigated. Adding a nonlinear electro-optic polymer as a defect layer, the alterations of the optical features are inspected. Results show that the defect layer insertion causes a resonant mode inside the PBGs. However, the location of the defect layer inside the crystal is very effective on both the frequency and width of the resonant mode. Tunability of the optical features is probed by taking into account of the dependencies to the wave incident angle, graphene chemical potential and the applied external voltage to the defect layer.