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介电常数呈正弦平方规律变化的一维光子晶体带结构 总被引:2,自引:1,他引:1
一维光子晶体是最简单的一类光子晶体。利用分子束外延生长技术,人们可以把两种折射率(或介电常数)不同的材料交替生长形成多层薄膜结构。由于对称性,人们就把这种多层薄膜材料近似当作一维光子晶体,并研究不同折射率情况下光子晶体的能带特征。假设介电常数呈正弦平方规律变化,光子的运动方程化为熟知的Mathieu方程。根据Bloch定理讨论了系统的能量分布,系统自动呈现出的能带结构,再现了光子晶体的周期性与能带特征。数值分析表明,在参数(δ,ε)平面上系统出现了一系列稳定和不稳定区(禁带)。当参数ε→0时,这些不稳定区退化为一点,给出了禁带中心频率,并用摄动法求解了方程的低阶不稳定区及其禁带宽度。结果表明,一阶和二阶不稳定区(禁带)宽度Δω1,2与介质的参数和入射光子频率有关。适当选择这些参数,可以有效地调节光子晶体的带结构,并按需要得到不同性能的光子晶体。 相似文献
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一维光子晶体禁带特性的研究 总被引:2,自引:2,他引:0
应用传输矩阵法研究了一维光子晶体的禁带特性,数值模拟得到了一维光子晶体TE模、TM模和TE/TM模禁带结构,计算结果表明,介质层的厚度发生变化时,禁带宽度发生变化。研究结果为一维光子晶体器件的设计提供了理论依据。 相似文献
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组合一维光子晶体全能反射器 总被引:18,自引:11,他引:7
为了能充分地展宽一维光子晶体的全方位禁带,从一维光子晶体禁带结构的特点出发,对于不发生Brewster效应的一维光子晶体,提出了通过两个或两个以上一维光子晶体的组合来实现和展宽一维光子晶体全方位禁带的理论依据和最佳组合方式.并给出了所提出的组合方式下相关参数的定量计算公式. 最后用传输矩阵法进行了数值模拟计算,对提出的组合方式进行验证,计算结果与预期结论符合很好. 相似文献
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基于能带理论设计了一种用于红外高反射的新型一维光子晶体。根据麦克斯韦方程的传输矩阵计算基础,得到了布洛赫波与入射光频率的色散关系,并由此构建了光子晶体能带结构。入射光波在介电常数周期变化结构中的布里渊区边界多次反射后会形成驻波,从而产生光子禁带。叠加3~5μm和8~12μm两种周期结构的光子晶体可以使光子禁带拓宽2.2×1013 Hz。在此基础上,选用折射率色散小的材料体系Si/ZnO设计并制备了13层一维光子晶体,该晶体在3~5μm和8~12μm红外波段的平均反射率在91.3%以上。实验结果与仿真结果吻合,验证了模型和理论的高可靠性。 相似文献
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提出了一种具有宽绝对禁带的一维磁性光子晶体结构,该结构由相同的折射率和物理厚度以及不同的波阻抗的两种磁性材料交替组合而成.通过传输矩阵法分析可得,相比于非磁性光子晶体,该光子晶体的禁带对入射角和偏振都不敏感,从而具有更宽的绝对禁带.合适地调节两种磁性材料的参数,增加两者波阻抗的差值,该光子晶体的绝对禁带宽度也相应地增加;调节两种磁性材料的物理厚度,其绝对禁带中心也会随之调整;最后,将两个满足上述条件的一维磁性光子晶体组成异质结构,其第一禁带宽度与禁带中心之间的比值可达到1.41以上. 相似文献
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Design for 2D anisotropic photonic crystal with large absolute band gaps by using a genetic algorithm 总被引:2,自引:0,他引:2
A 2-state genetic algorithm (GA) approach is used to design a two-dimensional (2D) anisotropic photonic crystal of square lattice with a maximal absolute band gap. The unit cell is devided equally into many small squares, and each filling pattern of squares with two dielectric materials corresponds to a binary number. As a numerical example, the GA gives a 2D Te structure with a relative width of the absolute band gap of about
. After a further optimization, a new structure is obtained with a relative width of the absolute band gap of about
.Received: 1 November 2003, Published online: 9 April 2004PACS:
42.70.Qs Photonic bandgap materials - 78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity) - 02.70.-c Computational techniques 相似文献
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In this paper, a rigorous theoretical analysis has been made to study the dispersion relation of EM waves in periodic ternary one-dimensional photonic crystal having two different structures. In one case we have chosen glass-plasma and ZnS in one unit cell and in other case we have considered glass-plasma and MgF2 in one unit cell. Using Kronig-Penney model the dispersion relation for proposed structures has been obtained and numerical results are presented in the form of dispersion curves. The dependence of photonic band gap (PBG) characteristics on plasma frequency, plasma width and the width of dielectric media are discussed in the light of frequency gap and cutoffs of binary one-dimensional plasma photonic crystal. An attempt has been made to show how the PBG characteristic of a particular structure changes when the dielectric materials of its unit cell is changed by the other dielectric material. It is found that the structure having glass-plasma-ZnS in unit cell is more useful for broad band filtering and other plasma functioning devices compared to the structure having glass-plasma-MgF2 in one unit cell. 相似文献
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基于传输矩阵法,数值研究了掺杂对一维光子晶体带隙特征的影响。研究表明:掺杂时,禁带中心会出现一导带,导带深度会随着掺杂位置、杂质折射率的变化而发生变化。当晶体结构给定时,总存在一个掺杂位置,使其禁带中心的导带深度达到最深;而对于给定的掺杂位置,当杂质折射率为某特定值时,禁带中心同样也会出现一个深度最深的导带,这种特性可应用于滤波器件和光学谐振腔的设计。 相似文献
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Zhong Yin Xiao Zi Hua Wang 《International Journal of Infrared and Millimeter Waves》2004,25(9):1309-1314
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. 相似文献
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Anirudh Banerjee 《International Journal of Infrared and Millimeter Waves》2008,29(11):1070-1082
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. 相似文献
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为减少坦克在实战中的红外辐射, 分析了坦克炮慢射后的辐射特征, 针对其炮管所辐射的特征波长在8-12 μm的电磁波,选用常见的SiO2和Si为介质, 并在考虑各自色散关系的基础上, 设计了具有光子晶体结构的防辐射涂层. 数值计算表明: 当两介质各取4层, 其几何厚度分别取1330和825 nm时,在8-12 μm 的范围内有一个严格的带隙. 当两介质的几何厚度增加, 带隙红移, 宽度增加, 反之亦然. 只要两介质的几何厚度变化不同时超过10%, 原带隙总是存在. 当介质层数取7-8时, 涂层在上述波长范围内的严格带隙已形成, 介质层数再增加, 带隙没有实质性的变化. 带隙结构对入射角的变化并不敏感. 相似文献