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1.
We investigate two types of honeycomb lattice two-dimensional plasma photonic crystals that possess large photonic band gaps in the presence of dissipation. We obtain a clear insight into the band structures and find imaginary parts of the eigenvalue band structure at the symmetry points display discontinuous behaviour when the filling factor of plasma in type-1 structure is low. Further more, we show how the photonic band gaps are affected by the normalized plasma frequency, radius of cylinder, dielectric constant and collision frequency. Our results demonstrate the band gap extension by increasing normalized plasma frequency in both type structures and radius of plasma cylinders in type-1 structure. The width of band gaps could also be enlarged by decreasing dielectric cylinder's radius. The bands shift toward lower frequencies when relative dielectric constant increases in both two types. These results may provide theoretical instructions to design new optoelectronic devices.  相似文献   

2.
在理想条件下,为了研究等离子体参数、填充率、入射角度和介质层相对介电常数对一维三元磁化等离子体光子晶体的禁带特性的影响,用由传输矩阵法计算得到的TE波任意角度入射时的左旋极化波(LCP)和右旋极化波(RCP)的透射系数来研究其禁带特性。结果表明,仅增加等离子体碰撞频率不能实现禁带宽度的拓展,改变等离子体频率、填充率和介质层的相对介电常数能实现对禁带宽度和数目的调谐。改变等离子体回旋频率能实现对右旋极化波的禁带的调谐,但对左旋极化波的禁带几乎无影响。入射角度的增大使得禁带低频区域带宽变大,而高频区域带宽则是将先减小再增大。  相似文献   

3.
Laxmi Shiveshwari 《Optik》2011,122(17):1523-1526
We consider the oblique propagation of electromagnetic waves in one-dimensional plasma dielectric photonic crystals, the superlattice structure consisting of alternating plasma and dielectric materials using transfer matrix method. Our results show that photonic band gaps for all polarizations can be obtained in one-dimensional plasma dielectric photonic crystals. These structures can exhibit a new type of band or gap, for the incidence angles other than normal incidence, near frequencies where the electric permittivity of the plasma layer changes sign. This new band or gap arises, from the dispersive properties of the plasma layer, only for TM polarized waves and its width increases with the increasing angle of incidence. This differential behaviour under polarization can be utilized in the design of an efficient polarization splitter. The band characteristic is affected by the plasma width, the plasma density, dielectric width, the dielectric constant of the dielectric medium and angle of incidence.  相似文献   

4.
《Physics letters. A》2019,383(25):3207-3213
In this paper, the plane wave expansion method is used to calculate the photonic band structure (PBS) for the transverse electric (TE) polarization in a two-dimensional hexagonal lattice composed air holes with cross-sections in the shape of equilateral triangles embedded in a GaAs background. We consider that the dielectric constant of GaAs is dependent on both hydrostatic pressure and temperature. Further, an increase can be observed in the width of the photonic band gap (PBG) while the lengths of the sides of the equilateral triangles are increased. When the pressure increases in the presence of a constant temperature, the dielectric constant of GaAs decreases; further, the PBS exhibits a more noticeable shift toward regions of higher frequencies than that observed while the temperature is increased at a given pressure. We also observed that the PBG obtained by rotating the triangular holes by an angle θ increases when compared against the results obtained for the lattice of holes without performing any rotation. In addition, the results obtained using the supercell technique denote that the position and width of the PBG remain unchanged while removing a triangular hole from the structure, denoting the presence of a defective band within the PBG.  相似文献   

5.
章海锋  刘少斌  孔祥鲲 《物理学报》2011,60(5):55209-055209
采用时域有限差分法(FDTD)中的分段线性电流密度卷积(PLCDRC)算法研究了TM波入射时二维非磁化等离子体光子晶体的禁带特性.从频域角度分析得到微分高斯脉冲的透射系数,并讨论该光子晶体的介质圆柱的介电常数、晶格常数、介质圆柱半径,周期常数和等离子体参数对其禁带特性的影响.结果表明,增加周期常数和等离子体碰撞频率不会改变禁带宽度,增加介质圆柱的相对介电常数和等离子体频率可以展宽禁带的宽度. 当填充率一定时,减小介质圆柱的半径和晶格常数可以实现禁带的拓展. 关键词: 等离子体 光子晶体 禁带 PLCDRC算法  相似文献   

6.
A standard plane-wave expansion method is used to investigate the photonic band structure of two-dimensional square and triangular lattices composed by cylindricalshell rods (GaAs rods surrounded by air shells) embedded in a semiconducting GaAs background. An analysis of the influence of geometry of the lattice basis is performed by changing inner and outer radii. The effect of dispersive dielectric responses as well as the influence of temperature and applied hydrostatic pressure to obtain efficient tunable bandgaps has also been considered. The presence of applied magnetic field is discussed as an efficient tool for tuning of the photonic band gaps in this kind of systems. The results suggest that a combination of a doped semiconductor constituent with an anisotropic geometry provides an efficient realization of photonic systems with tunable bandgaps.  相似文献   

7.
章海锋  刘少斌  孔祥鲲 《物理学报》2011,60(2):25215-025215
采用等离子体的分段线性电流密度卷积时域有限差分算法研究了横磁波入射时具有单一线缺陷的二维非磁化等离子体光子晶体的缺陷模特性. 从频域角度分析得到微分高斯脉冲的透射系数,并讨论该光子晶体的晶格常数、介质圆柱半径、周期常数、缺陷层参数和等离子体参数对缺陷模特性的影响. 结果表明,改变周期常数、缺陷层位置和等离子体碰撞频率不会改变缺陷模的频率,改变缺陷层介质圆柱的相对介电常数、半径和缺陷层到介质层的中心距离可以在不改变禁带宽度的前提下实现对缺陷模的调节,改变晶格常数、介质圆柱半径和等离子体频率能同时实现对禁带宽度和缺陷模的调节. 关键词: 等离子体 光子晶体 缺陷模 时域有限差分算法  相似文献   

8.
The tunable two-dimensional photonic crystals band gap, absolute photonic band gap and semi-Dirac point are beneficial to designing the novel optical devices. In this paper, tunable photonic band gaps structure was realized by a new type two-dimensional function photonic crystals, which dielectric constants of medium columns are functions of space coordinates. However for the two-dimensional conventional photonic crystals the dielectric constant does not change with space coordinates. As the parameter adjustment, we found that the photonic band gaps structures are dielectric constant function coefficient, medium columns radius, dielectric constant function form period number and pump light intensity dependent, namely, the photonic band gaps position and width can be tuned. we also obtained absolute photonic band gaps and semi-Dirac point in the photonic band gaps structures of two-dimensional function photonic crystals. These results provide an important theoretical foundation for design novel optical devices.  相似文献   

9.
We theoretically study the effect of the dielectric background in two-dimensional metallo-dielectric photonic crystals. The metallo-dielectric photonic crystal consists of a square lattice of circular metallic rods embedded into a dielectric background. We calculate the photonic band structure by means of the plane wave method and the frequency-dependent finite-difference time-domain method. The transfer matrix method is used to obtain the reflectivity characteristics. Results show that the band structures shift toward lower frequencies and become flatter when the background dielectric constant increases. In addition, degeneracy can be broken and new gaps can be created in function of the dielectric background. We also found that the relative band gap width Δω/ωg grows with increasing background dielectric constant and widths as large as 42.3% and 13.8% for the second and third band gaps can be achieved for εb = 9. We have investigated the origin of the new gap in these structures by studying the electric-field distribution at the band edges for the first five modes.  相似文献   

10.
Xiang-kun Kong  Hong-wei Yang 《Optik》2010,121(20):1873-1876
The anomalous dispersion in one-dimensional plasma photonic crystals (1-DPPCs) is studied. The width of band pass and band gap are compressed, the phase velocity decreases and the cup-off frequency comes close to the frequency of plasma when EM wave oblique incidence on 1-DPPCs. The band gaps are affected by the thickness of plasma, the dielectric constant of the dielectric material, the plasma density and the angle of incidence. Superluminal negative group velocity is discovered in this study. This character is interesting for scientists and may have a potential application.  相似文献   

11.
Dispersion properties of two types of two-dimensional periodically magnetized plasma array structures with square lattices have been investigated by using plane wave expansion method. It is found that two different regions of flatbands and photonic band gaps occur in the TE polarization due to the external magnetic field. The two types of system can be seen as a kind of unusual plasma photonic crystals. The results show that not only the location of flatbands but also the position and bandwidth of photonic band gaps can be tuned by external magnetic field. The cutoff frequency decreases as external magnetic field increases. The edge of two different of flatbands regions and cutoff frequency shift downward to lower frequencies obviously with increasing plasma collision frequency, while they shift upward to higher frequencies notably with increasing plasma frequency. The filling factor has little effect on the location of flatbands regions. The width of flatbands regions and photonic band gaps are almost unchanged by increasing filling factor, but the number of ominidirectional photonic band gap for type-1 structure plasma photonic crystals can be effectively controlled by adjusting filling factor. It is worth to be noted that the first band gaps above the cutoff frequencies in ГX and ГM direction for two types of PPCs can be modulated by the parameters as mentioned above, and the relative bandwidth of band gap in ГX direction is wider than the one in ГM direction. The results may provide theoretical instructions to design new tunable photonic crystals devices.  相似文献   

12.
Complete photonic band gaps (PBGs) are found in one-dimensional ternary photonic crystals (1D TPCs) composed of an ordinary dielectric and single negative metamaterials. The proposed TPC gives omni directional PBG completely independent of polarizations dependent weekly on angle of incidence. Here the choice of different parameters of TPC is done in such a way so that it eliminates the Brewster's-angle transmission resonance, thus allowing a complete 3D PBG. It exhibits a photonic band or gap near frequencies where either the magnetic permeability or the electric permittivity of the metamaterial changes sign, whose width increases with the increasing angle of incidence. These result from the dispersive properties of the metamaterials and disappear for the particular case of propagation along the stratification direction. The results are discussed in terms of incident angle, layer thickness, dielectric constant of the dielectric material for TE and TM polarizations.  相似文献   

13.
We obtain the photonic bands and intrinsic losses for the triangular lattice three-component two- dimensional (2D) photonic crystal (PhC) slabs by expanding the electromagnetic field on the basis of waveguide modes of an effective homogeneous waveguide. The introduction of the third component into the 2D PhC slabs influences the photonic band structure and the intrinsic losses of the system. We examine the dependences of the band gap width and gap edge position on the interlayer dielectric constant and interlayer thickness. It is found that the gap edges shift to lower frequencies and the intrinsic losses of each band decrease with the increasing interlayer thickness or dielectric constant. During the design of the real PhC system, the effect of unintentional native oxide surface layer on the optical properties of 2D PhC slabs has to be taken into consideration. At the same time, intentional oxidization of macroporous PhC structure can be utilized to optimize the design.  相似文献   

14.
电磁波在周期介质中的传播及二维光子晶体的光子带结构   总被引:5,自引:4,他引:1  
光子晶体是光学与凝聚态物理交叉的新领域,也是近年来应用物理学的一个重要研究领域,它是一种由介电常数高的(低的)介质在另一种介电常数低的(高的)背景介质中周期排列所组成的人造多维周期结构材料,能够产生光子带隙。频率落在带隙内的光在晶体里沿任何方向都不能传播,因而具有能够抑制原子、分子的自发辐射等诱人的光电子学特性,在基础研究和实际应用上都有着巨大的潜力。本文在这一领域里进行了富有成效的研究,获得了很好的结果。主要有:(1)利用平面波展开方法来计算二维光子晶体的带隙结构。首先,我们设计正方晶胞的二维光子晶体模型。设x3方向为介质柱的轴方向,二维周期结构在x1-x2平面上。晶胞的晶格常数为a,半径为r,介质柱和空气柱的介电常数分别为εa=17和εb=1,a>2r。设计的核心思想是通过降低光子晶体结构的对称性,消除光子能带在晶体的布里渊区高对称点上的本征简并。(2)对于二维光子晶体的电磁波理论及周期介质中的Bloch波解做了详细的推导,给出了光子晶体中禁带存在的理论依据。同时以正方格子晶格的二维光子晶体为例,验证了电介质在空气圆孔中的排列存在E偏振和H偏振的光子带隙重叠区,称为绝对光子带隙。对于二维的光子晶体,两种本征偏振模式的光子能带结构可以独立地调节,以实现两者的光子带隙的最优重叠, 从而大大提高了二维光子晶体的完全带隙宽度。  相似文献   

15.
In this paper we analyze theoretically how the introduction of the third component into the two-dimensional photonic crystal influences the photonic band structure and the density-of-states of the system. We consider the periodic array of cylindrical air rods in a dielectric, and the third medium is introduced as a ring-shaped intermediate layer of thickness d and dielectric constant i between the air pores and the dielectric background. Using the plane wave method, we have obtained the band structures for the 2D triangular lattice photonic crystals. The dependencies of TE and TM band gaps’ widths and gaps’ edges position on the interlayer dielectric constant and interlayer thickness were analyzed. In the framework of this approach, we have estimated the influence of the surface oxide layer on the band structure of macroporous silicon. We observed the shift of the gaps’ edges to the higher or lower frequencies, depending on the interlayer thickness and dielectric constant. We have shown that the existence of a native oxide surface layer should be taken into consideration to understand the optical properties of 2D photonic crystals, particularly in macroporous silicon structures.  相似文献   

16.
通过增加外磁场来调控等离子体光子晶体的光子带隙结构,采用时域有限差分算法分析了由本征层为磁化等离子体层和其他电介质材料层交替堆叠而成的磁化等离子体光子晶体的光子带隙结构,数值模拟中采用完全匹配层吸收边界条件以防止边界的反射。由于外磁场的法拉第磁光效应,使等离子体的介电常数随着外磁场的变化而改变。数值结果表明,等离子体光子晶体的带隙特性在一定的频率范围相应地得到调节,实现了频率低于等离子体频率的电磁波也能在等离子体中传播。  相似文献   

17.
宗易昕  夏建白  武海斌 《中国物理 B》2017,26(4):44208-044208
An improved plan-wave expansion method is adopted to theoretically study the photonic band diagrams of twodimensional(2D) metal/dielectric photonic crystals.Based on the photonic band structures,the dependence of flat bands and photonic bandgaps on two parameters(dielectric constant and filling factor) are investigated for two types of 2D metal/dielectric(M/D) photonic crystals,hole and cylinder photonic crystals.The simulation results show that band structures are affected greatly by these two parameters.Flat bands and bandgaps can be easily obtained by tuning these parameters and the bandgap width may reach to the maximum at certain parameters.It is worth noting that the hole-type photonic crystals show more bandgaps than the corresponding cylinder ones,and the frequency ranges of bandgaps also depend strongly on these parameters.Besides,the photonic crystals containing metallic medium can obtain more modulation of photonic bands,band gaps,and large effective refractive index,etc.than the dielectric/dielectric ones.According to the numerical results,the needs of optical devices for flat bands and bandgaps can be met by selecting the suitable geometry and material parameters.  相似文献   

18.
通过增加外磁场来调控等离子体光子晶体的光子带隙结构,采用时域有限差分算法分析了由本征层为磁化等离子体层和其他电介质材料层交替堆叠而成的磁化等离子体光子晶体的光子带隙结构,数值模拟中采用完全匹配层吸收边界条件以防止边界的反射。由于外磁场的法拉第磁光效应,使等离子体的介电常数随着外磁场的变化而改变。数值结果表明,等离子体光子晶体的带隙特性在一定的频率范围相应地得到调节,实现了频率低于等离子体频率的电磁波也能在等离子体中传播。  相似文献   

19.
等离子体光子晶体的FDTD分析   总被引:21,自引:0,他引:21       下载免费PDF全文
刘少斌  朱传喜  袁乃昌 《物理学报》2005,54(6):2804-2808
等离子体光子晶体是等离子体和介质(真空)构成的人工周期性结构.用分段线性电流密度 递归卷积时域有限差分(PLCDRC-FDTD)算法分析了等离子体光子晶体和缺陷等离子体光子 晶体.从时域的角度分析了高斯脉冲在等离子体光子晶体中的传播过程,给出了时域反射和 透射波形.然后,从频域的角度分析了等离子体光子晶体和带缺陷的等离子体光子晶体的电 磁反射系数和透射系数.计算表明,等离子体光子晶体对频率小于等离子体频率的低频电磁 波几乎完全反射,而透射的电磁波则为频率高于等离子体频率的电磁波.在高频,等离子体 光子晶体则出现类似一般光子晶体的光子带隙特性. 关键词: 等离子体 光子晶体 时域有限差分法 等离子体光子晶体  相似文献   

20.
In this paper, the properties of the omnidirectional photonic band gap (OBG) realized by one-dimensional (1D) photonic crystals (PCs) with a staggered structure which is composed of plasma and isotropic dielectric layer have been theoretically studied by the transfer matrix method (TMM). From the numerical results, it has been shown that such OBG is insensitive to the incident angle and the polarization of electromagnetic wave (EM wave), and the frequency range and central frequency of OBG can be effectively controlled by adjusting the plasma frequency, the average thickness of plasma layer, the average thickness of dielectric layer and staggered parameters, respectively. The frequency range of OBG can be notably enlarged with increasing the plasma frequency, average thickness of plasma layer, respectively. Moreover, the bandwidth of OBG can be narrowed with increasing the average thickness of dielectric layer. Changing staggered parameters of dielectric and plasma layer means that the OBG can be tuned. It is shown that 1D plasma dielectric photonic crystals (PPCs) with such staggered structure have a superior feature in the enhancement of frequency range of OBG compared with the conventional 1D binary PPCs. This kind of OBG has potential applications in filters, microcavities, and fibers, etc.  相似文献   

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