共查询到20条相似文献,搜索用时 360 毫秒
1.
2.
3.
采用自组装法制备了聚苯乙烯(PS)微球三维光子晶体结构,通过在PS微球悬浮液中掺入不同浓度的二氧化硅大球,实现了光子晶体结构从有序向无序过程的转变。通过对这些样品的透射、反射进行测量和分析,发现无序效应对光子晶体的光子响应特性具有极大的影响,随着无序程度的增加,高频波段的透射率急剧下降,低频波段的法布里-珀罗振荡消失,光子带隙蓝移且逐渐消失;而在掺杂浓度为0.02%(质量分数)时,光子晶体带隙中心的最低透射率从10%下降到1%,且反射单峰随着探测角度的增大而分裂为双峰。这有助于基于介质球三维光子晶体沿Γ-L方向透射消光,促进其在新型光学器件领域的应用发展。 相似文献
4.
The universal condition for the formation of omnidirectional band gaps (OBG) in photonic crystal (PC) was derived with consideration
of permeability of the materials. And it was found that there are four kinds of PCs: one of them has no OBG, and one always
possesses OBG. For the other two kinds of PCs, there are OBG for only TM or TE waves respectively. Moreover, in all PCs, the
OBG can be broadened by decreasing the refractive index of the ambient medium or/and increasing the contrast between the wave
impedances of the component materials of the PC.
PACS 42.70.Qs; 71.20.Tx 相似文献
5.
基于光子晶体来构筑偏振无关光二极管在光电集成领域具有重大的应用价值.首先提出了一种环形孔光子晶体,能带结构显示其对横电及横磁模式同时展现出显著的方向带隙.以此构建了三角形状的环形孔光子晶体,利用时域有限差分法计算其透过谱及场分布图,发现该结构能实现偏振无关单向传输特性,然而正向透过率太低(约20%).进一步引入尺寸较小的三角形状的环形孔光子晶体构成光子晶体异质结结构,有效地提高了偏振无关单向传输性能,正向透过率增大了一倍.通过界面结构的调整,正向透过率进一步增大,优化后的环形孔光子晶体异质结结构能同时对类横电及类横磁模式入射光实现单向传输,且正向透过率达到了44%. 相似文献
6.
Three-dimensional photonic crystal (PC) heterostructures with high
quality are fabricated by using a pressure controlled isothermal
heating vertical deposition technique. The formed heterostructures
have higher quality, such as deeper band gaps and sharper band
edges, than the heterostructures reported so far. Such a significant
improvement in quality is due to the introduction of a thin
TiO2 buffer layer between the two constitutional PCs. It is
revealed that the disorder caused by lattice mismatch is
successfully removed if the buffer layer is used once. As a result,
the formed heterostructures possess the main features in
the band gap of constitutional PCs. The crucial role of the thin buffer
layer is also verified by numerical simulations based on the
finite-difference time-domain technique. 相似文献
7.
Band structures of one-dimensional(1D)photonic crystals(PCs)containing dispersive left-handed metamaterials are studied theoretically.The results show that the structure possesses a type of photonic band gap originating from total internal reflection(TIR).In contrast to photonic band gaps corresponding to zero average refractive index and zero phase.the TIR gap exhibits sharp angular effect and has no polarization effect.It should also be noted that band structures of transverse electric(TE) and transverse magnetic(TM) mode waves are exactly the same in the PCs we studied. 相似文献
8.
光子晶体是介电常数(折射率)随光波长大小周期性巨大变化的人工晶体。光子晶体的诞生使人类操控光子由梦想成为现实。光子晶体结构对置于光子晶体中的荧光客体自发辐射速率和荧光强度具有重要的调制作用。与半导体晶格对电子波函数的调制相类似,光子带隙材料能够调制具有相应波长的电磁波——当电磁波在光子带隙材料中传播时,由于存在布拉格散射而受到调制,电磁波能量形成能带结构。能带与能带之间出现带隙,即光子带隙。所具能量处在光子带隙内的光子,不能进入该晶体。本文将在综述这一领域国际上的重要研究进展基础上,重点介绍本课题组在镧系氧化物三维晶体的自组装与光子带隙对稀土离子自发辐射调制方面的研究成果。 相似文献
9.
10.
We propose a type of photonic heterostructure by combining dielectric one-dimensional (1D) defective photonic crystals (PCs)
and magnetic 1D defective PCs. Both of the two PCs consist of alternating positive-index-material (PIM) layers with a negative-index-material
(NIM) defect layer. It is demonstrated by transfer matrix method that there is a polarization- and direction-independent defect
mode in a wide incident-angle range within Bragg gaps in the heterostructure. The field distributions prove that the dielectric
1D defective PC benefits to achieve the approximately omnidirectional defect mode for TE waves while the magnetic 1D defective
PC benefits for TM waves. Such a structure is useful for designing polarization-independent and omnidirectional or large incident
angle narrow-passband filters in optical devices. 相似文献
11.
Munazza Zulfiqar Ali 《中国光学快报(英文版)》2012,(7):69-72
Wave propagation is studied in structures consisting of alternate left- and right-handed layers.Bragg gap and zero-n gap appear in different frequency regions of the structure.The periodicity of the structure is broken by simply reversing the order of the layers in one half of the structure,resulting in defect modes located inside the zero-n gap and Bragg gap.These modes can be made very narrow by adding more layers in the structure.The defect mode located inside the zero-n gap is sensitive to the symmetry of the structure and insensitive to the angle of incidence of the incoming radiation.Multiple modes are also generated inside the gaps by repeating the structural pattern.Thus,a simple structure can be used for single and multiple modes that are important for different applications. 相似文献
12.
拓扑绝缘体是当前凝聚态物理领域研究的热点问题.利用石墨烯材料的特殊能带特性来实现拓扑输运特性在设计下一代电子和能谷电子器件方面具有较广泛的应用前景.基于光子与电子的类比,利用光子拓扑材料实现了确定性界面态;构建了具有C_(6v)。对称性的类似石墨烯结构的的光子晶体复杂晶格;通过多种方式降低晶格对称性来获得具有C_(3v),C_3,C_(2v)和C_2对称的晶体,从而打破能谷简并实现全光子带隙结构;将体拓扑性质不同的两种光子晶体摆放在一起,在此具有反转体能带性质的界面上,实现了具有单向传输特性的拓扑确定性界面态的传输.利用光子晶体结构的容易加工性,可以简便地调控拓扑界面态控制光的传播,可为未来光拓扑绝缘体的研究提供良好的平台. 相似文献
13.
14.
Lopetegi T. Laso M.A.G. Gonzalo R. Erro M.J. Falcone F. Benito D. Garde M.J. De Maagt P. Sorolla M. 《Optical and Quantum Electronics》2002,34(1-3):279-295
Recently, new promising periodic structures called photonic crystals (PCs), or more appropriately electromagnetic crystal (ECs), for the microwave and millimetre wave range, have been considered for both microwave and photonic applications. Planar microstrip waveguides are very attractive in microwave engineering and several innovative designs have been proposed for them to expand the scope of application of the new PC concepts to the microwave domain. We review some of these microstrip EC structures looking at them as counterparts of their analogues in optical wavelengths. Moreover, very recent solutions that open new promising applications both in microwave and millimetre wave integrated circuits and antennas are presented. 相似文献
15.
The photonic band gaps in one-dimensional photonic crystals (PCs) are theoretically investigated. A new method to broaden the photonic band gaps is introduced. Based on the similar method, a kind of photonic crystals is constructed to generate photonic band gaps with proportioned central frequencies. This technology can be used for designing nonlinear PCs for harmonic generation. 相似文献
16.
Dispersion characteristics of two-dimensional unmagnetized dielectric plasma photonic crystal 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper studies dispersion characteristics of the
transverse magnetic (TM) mode for two-dimensional unmagnetized
dielectric plasma photonic crystal by a modified plane wave method.
First, the cutoff behaviour is made clear by using the
Maxwell--Garnett effective medium theory, and the influences of
dielectric filling factor and dielectric constant on effective
plasma frequency are analysed. Moreover, the occurence of large gaps in
dielectric plasma photonic crystal is demonstrated by comparing the
skin depth with the lattice constant, and the influence of plasma
frequency on the first three gaps is also studied. Finally, by using
the particle-in-cell simulation method, a transmission curve in the
\Gamma -X direction is obtained in dielectric plasma photonic
crystal, which is in accordance with the dispersion curves
calculated by the modified plane wave method, and the large gap between
the transmission points of 27~GHz and 47~GHz is explained by
comparing the electric field patterns in particle-in-cell
simulation. 相似文献
17.
《Physics letters. A》2014,378(18-19):1326-1332
Designing dielectric systems to create omnidirectional band gaps (OBGs) is an attractive topic in the field of photonic band gap (PBG) structures. In this Letter, we propose a new approach to create OBGs by ternary photonic heterostructures (TPHs) composed of three kinds of materials with different refractive indices and obtain the formulae of the structures of TPHs, i.e., those of the thicknesses of materials and the number of sub-ternary photonic crystals. It may provide a powerful technique for designing the structures being able to produce OBGs by use of usual materials, lowcost materials, and materials with low refractive indices, etc. 相似文献
18.
利用传输矩阵法研究了异质双周期结构一维光子晶体的带隙结构和光学传输特性。此光子晶体能形成512~960 nm的含5个极窄透射峰的光子带隙。重点研究了一种材料为复折射率时的光学传输特性,以及当结构发生轴向应变时的"介观压光效应"。结果表明:当复折射率虚部为负时,透射峰随虚部绝对值的增大先增大后减小,甚至出现衰减;虚部为正时,发生吸收现象。当光子晶体发生轴向应变时,透射峰随应变量的增加呈现近似L形变化,应变量很小时透射率几乎线性减小,波长越大透射峰变化越缓慢。 相似文献
19.
Shao-Wei Wang Wei Lu Xiao-Shuang Chen Mei Zhou Xue-Chu Shen 《International Journal of Infrared and Millimeter Waves》2003,24(6):963-971
Photonic band gap (PBG) in two-dimensional (2D) anisotropic photonic crystal (PC) constructed of rectangular bars has been numerically studied by using Transfer Matrix Method (TMM). The results show that the PBG is bounded by the lower band edge of TE wave and the upper band edge of TM wave. Its width simply increases with increasing of shape parameter . It reaches a maximum value as the structure degenerates into its 1D counterpart, due to the complete overlapping of gaps in TE and TM waves. The anisotropy in PC structure results in the transmission anisotropic property. One can design the PBG structures in different incident directions to match their application demand. 相似文献
20.
运用FDTD(时域有限差分法)研究了弹性波/声波通过二维正方形排列的铁/水声子晶体的传播特性.发现铁/水声子晶体在高频范围存在完全带隙,软包层铁/水声子晶体在低频范围出现共振带隙,它们分别对应于不同的带隙形成机理.通过铁/水声子晶体和软包层铁/水声子晶体的组合,可以得到从高频到低频的组合宽带隙结构,从而达到在更宽频范围内控制弹性波传播的目的;而且通过调整包层的厚度、铁芯的大小、以及填充率等结构参数,可以有效地调节组合宽带隙的频率结构. 相似文献