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1.
In this Letter, based on ancient Peano curves we construct four kinds of interesting Peano derivative networks composed of one-dimensional (1D) waveguides and investigate the optical transmission spectra and photonic attenuation behavior of electromagnetic (EM) waves in one- and two-segment-connected networks. It is found that for some two-segment-connected networks large photonic band gaps (PBGs) can be created and the widths of large PBGs can be controlled by adjusting the matching ratio of waveguide length and are insensitive to generation number. Diamond- and hexagon-Peano networks are good selectable structures for the designing of optical devices with large PBG(s) and strong attenuation(s). 相似文献
2.
A novel structure of two-dimensional (2D) square-lattice photonic crystal (SLPC) composed of Taiji-shaped dielectric rods imbedded in air is constructed and the properties of absolute photonic band gap (PBG) are theoretically analyzed in both the number and width by Plane Wave Expansion Method (PWM). By comparing the absolute PBGs in 2D SLPCs consisting of four shapes of rods with different symmetries (circle, button, semicircle and Taiji) at the same filling ratio, we find that both the number and width of absolute PBG significantly increase with the breaking of scatterer's symmetry, and the Taiji-shaped rods with the poorest symmetry can attain both the most number and the largest width of absolute PBGs. Additionally, we also study the influence of dielectric constant ε and three geometric parameters of Taiji-shaped scatterer on the absolute PBG and discover that the SLPC with Taiji-shaped rods can generate at most nine absolute PBGs and the largest absolute PBG with the width 0.0485 (ωa/2πc). 相似文献
3.
We present a design for a photonic crystal (PC) all-optical micro-chip based on a three-dimensional (3D) inverse opal heterostructure intercalated with a two-dimensional (2D) triangular lattice photonic crystal slab. Within the 2D micro-chip layer, we demonstrate single-mode (diffractionless) waveguiding of light in air, throughout a bandwidth of more than 70 nm near 1.55 μm. This suggests that inverse opal photonic band gap (PBG) materials can facilitate on-chip optical networking functions over the telecommunication frequency band used in current-day optical fibers. 相似文献
4.
Bipin K. Singh Pawan Kumar Praveen C. Pandey 《Applied physics. B, Lasers and optics》2014,117(3):947-956
We have demonstrated control of the photonic band gaps (PBGs) in 1-D photonic crystals using linear graded index material. The analysis of PBG has been done in THz region by considering photonic crystals in the form of ten periods of second, third and fourth generation of the Fibonacci sequence as unit cell. The unit cells are constituted of two kinds of layers; one is taken of linear graded index material and other of normal dielectric material. For this investigation, we used a theoretical model based on transfer matrix method. We have obtained a large number of PBGs and their bandwidths can be tuned by changing the grading profile and thicknesses of linear graded index layers. The number of PBGs increases with increase in the thicknesses of layers and their bandwidths can be controlled by the contrast of initial and final refractive index of the graded layers. In this way, we provide more design freedom for photonic devices such as reflectors, filters, optical sensors, couplers, etc. 相似文献
5.
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. 相似文献
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提出了一种新型的非对称性散射体的二维六角晶格光子晶体结构–-太极形介质柱光子晶体. 利用平面波展开法从理论研究这种光子晶体结构的能带特性以及结构参数对完全禁带的影响. 研究表明:散射体对称性的打破, TE模和TM模能带宽度和数目都会有所增加, 有益于获得更宽的完全禁带以及更多条完全禁带.通过参数优化, 发现在ε = 17, R=0.38 μm, r=0.36R, θ = 0° 时, 获得最大完全带隙宽度0.0541(ωa/2πc); 在ε = 16, R=0.44, r=0.2R, θ = 0°时, 光子晶体完全带隙数目最多达到8条.
关键词:
光子晶体
禁带
平面波展开 相似文献
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10.
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
11.
In this paper, by means of the network equation and generalized eigenfunction method we investigate the optical transmission spectra and attenuation behavior of electromagnetic (EM) waves in multiconnected Peano networks composed of one-dimensional (1D) waveguides. It is found that for some two-segment-connected networks a very large photonic band gap (PBG) can be created in the middle of a frequency period and the width of the large PBG can be controlled by adjusting the matching ratio of waveguide length, d2 : d1. When d2 : d1 = 2 : 1, the width of the large PBG is bigger than half of frequency period. The influence of generation on the width and attenuation of the large PBG are also studied and the numerical results demonstrate that the first-generation Peano network with d2 : d1 = 2 : 1 is a good selectable structure for the designing of optical devices with large PBG and strong attenuation. 相似文献
12.
In this paper, the properties of anisotropic photonic band gaps (PBGs) for three-dimensional (3D) photonic crystals (PCs) composed of the anisotropic positive-index materials (the uniaxial materials) and the epsilon-negative (ENG) materials with body-centered-cubic (bcc) lattices are theoretically studied by a modified plane wave expansion (PWE) method, which are the uniaxial materials spheres inserted in the epsilon-negative materials background. The anisotropic photonic band gaps (PBGs) and one flatbands region can be achieved in first irreducible Brillouin zone. The influences of the ordinary-refractive index, extraordinary-refractive index, filling factor, the electronic plasma frequency, the dielectric constant of ENG materials and the damping factor on the properties of anisotropic PBGs for such 3D PCs are studied in detail, respectively, and some corresponding physical explanations are also given. The numerical results show that the anisotropy can open partial band gaps in such 3D PCs with bcc lattices composed of the ENG materials and uniaxial materials, and the complete PBGs can be obtained compared to the conventional 3D PCs containing the isotropic materials. The calculated results also show that the anisotropic PBGs can be manipulated by the parameters as mentioned above except for the damping factor. Introducing the uniaxial materials into 3D PCs containing the ENG materials can obtain the larger complete PBGs as such 3D PCs with high symmetry, and also provides a way to design the tunable devices. 相似文献
13.
Qi Ya Wei-Qiang Chen Xian-Zi Dong Thomas Rodgers Sana Nakanishi Satoru Shoji Xuan-Ming Duan Satoshi Kawata 《Applied Physics A: Materials Science & Processing》2008,93(2):393-398
A 3D woodpile photonic crystal (PhC) composed of two parts with different periodic parameters was fabricated with a novel
photoresist containing photoresponsive azobenzene moieties by multiphoton polymerization. Dual photonic band gaps (PBGs) were
experimentally measured, which were attributed to two independent parts of the 3D PhC with different periodicities. Under
light irradiation, PBG tuning of 36 nm was obtained, and this tuning behavior showed good reversibility. 相似文献
14.
Jian Shen Shiyang Liu Rong Cao Xin Fan Junjie Du Huaiwu Zhang Zhifang Lin Siu-Tat Chui John Q. Xiao 《Applied Physics A: Materials Science & Processing》2011,105(4):789-793
We experimentally studied magnetically controllable photonic band gaps (PBGs) in two-dimensional magnetic photonic crystals
consisting of ferrite rods. Besides the conventional PBG that relates to Bragg scattering, two other types of PBG, resulting
from magnetic surface plasmon (MSP) resonance and spin-wave resonance, respectively, are observed. The PBG due to MSP resonance
is particularly interesting because of its analogy to surface plasmon in metal; furthermore, it is shown to be completely
tunable by an external static magnetic field from both an experimental and a theoretical point of view. 相似文献
15.
Block copolymers (BCPs), which self-organize into ordered 1-, 2- and 3-dimensional periodic equilibrium structures, can exhibit
photonic band gaps (PBGs). In this paper, cylinder microdomain nanoporous films are proposed to be treated as a new kind of
2-dimensional BCP based photonic crystal. The minor component of the nanoporous films has been removed chemically with only
pores left in order to enhance their dielectric constant contrast, which provides a new solution to achieve necessary PBG
properties with BCPs. The finite-difference time-domain (FDTD) method is used to investigate band features of this kind of
photonic crystal theoretically. It is noted that the complete band gaps for the H polarization are obtained, although for
the E polarization only the incomplete gaps exist. In addition, the gap map of the PBG materials is presented and its characteristics
are analyzed.
PACS 42.70.Qs; 42.70.Jk; 42.25.Bs 相似文献
16.
Y. Li C. Wang X. Lü M. Hu Y. Chen B. Liu L. Chai 《Applied physics. B, Lasers and optics》2007,86(2):235-242
Photonic crystal fibers (PCFs) can guide light by the photonic bandgap (PBG) effect created by the periodically arranged air
holes in the cladding. In this paper, the bandgap properties of Kagomé photonic crystal fibers (KPCFs) are investigated in
detail. First, the bandgap properties of PCFs based on the basic Kagomé lattice are analyzed and compared with the PBGs of
PCFs based on honeycomb and triangular lattices. We highlight the similarities between KPCFs and honeycomb PCFs in their PBGs,
both having air-guiding regions only at very large air filling fractions (AIFs), whereas the PBGs of triangular PCFs can have
large air-guiding regions at smaller AIFs due to the difference in the gap structure. In the second half of this paper, we
show how the PBGs of KPCFs can be modified by introducing an extra air hole into the vacant space of the original lattice.
In particular, KPCFs with medium-sized air holes can be designed to guide air by introducing extra air holes of a larger size.
The air-guiding regions of KPCFs with very large air holes can also be greatly extended by the extra air holes. These air-guiding
regions occur at higher normalized frequencies, resulting in larger air hole pitches favorable for fabrication.
PACS 42.70.Qs; 42.25.Bs; 42.81.Qb 相似文献
17.
Band gaps of two-dimensional photonic crystal structure using conjugated polymer (3-octylthiophenes) 总被引:1,自引:0,他引:1
The possibility of using conjugated polymer (3-octylthiophenes, P3OT) as two-dimensional (2D) photonic band gap crystals was investigated. The different aspects were examined of the absolute photonic band gap (PBG) formation for 2D photonic crystals (PCs) consisting of P3OT pillars in air. The formation of PBG was exhibited and confirmed by a calculation of transfer matrix method (TMM). It was found that P3OT triangular structure could be good candidate for absolute inhibition of reflection in ultraviolet frequency region for given orientation. 相似文献
18.
Photonic amorphous diamond structure with a 3D photonic band gap 总被引:1,自引:0,他引:1
We report that a full three-dimensional (3D) photonic band gap (PBG) is formed in a photonic amorphous structure in spite of complete lack of lattice periodicity. It is numerically shown that the structure "photonic amorphous diamond" possesses a sizable 3D PBG (18% of the center frequency for Si-air dielectric contrast) and that it can confine light at a defect as strongly as conventional photonic crystals can. These findings present important new insight into the origin of 3D PBG formation and open new possibilities in developing 3D PBG materials. 相似文献
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光子带隙是指某一频率范围的波不能在周期变化的空间介质中传播,即这种结构本身存在“禁带”,并已成功地应用于滤波器、放大器和混频器等器件的设计中.此前,许多专家都致力于提高带隙的反射率,但其只能逐渐接近1.本文在囚禁于一维光晶格中的冷原子介质中实现两个可调光子带隙,并通过选择两基态为精细结构的三能级∧型原子系统,考虑自发辐射相干效应来探究这两个带隙的反射率.适当调节参数,探测场出现增益,从而获得较高反射率的带隙结构,甚至可以超过1.此外,两个带隙反射率还可以通过调节偶极矩之间的夹角以及非相干驱动场强度等参数来操控. 相似文献