共查询到20条相似文献,搜索用时 122 毫秒
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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. 相似文献
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利用平面波展开法对二维六角晶格结构磁性光子晶体的带隙特性进行了研究,给出其能带结构分布图,并与非磁性介质构成的光子晶体进行了比较.结果表明,由磁性材料构成的光子晶体更易出现带隙,磁导率对带隙结构影响很大.空气背景磁性散射子情况,磁导率增加较小时,二个绝对光子带隙宽度逐渐减小,直至消失.继续增加磁导率,在较低频率范围内出现一个绝对光子带隙,占空比逐渐加大,且最佳填充系数基本保持不变.磁性背景空气散射子,类似地在较低频率范围内也出现了一个绝对光子带隙.磁性背景非磁性散射子与空气背景磁性散射子情况相似. 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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应用传输矩阵法研究了由电磁感应透明材料构成的一维光子晶体带隙结构.计算结果表明:通过改变控制光的拉比频率可以调控一维光子晶体的禁带宽度.随着拉比频率的增加,EIT原子气体的相对折射率也随着增加.随着拉比频率的逐渐加大,光子晶体的禁带宽度变得越来越窄,但变化变得越来越慢,即增加相同大小的拉比频率其影响越来越小. 相似文献
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在高频区存在巨带隙的长方晶格二维光子晶体 总被引:15,自引:12,他引:3
本文利用降低光子晶体的对称性来提高绝对禁带宽度, 提出两种长方结构长方介质柱二维光子晶体, 用快速平面波展开法研究其高频区的带结构.经参数优化发现, 长方晶格包含一套介质柱时, 最大绝对禁带宽度Δω为0.1265ωe(ωe=2πc/a, a为晶格常数, c为光速), 绝对禁带中心频率ωmid为1.9256ωe, Δω/ωmid=6.6%; 当长方晶格包含两套介质柱时, 最大绝对禁带宽度为0.203ωe, 绝对禁带中心频率为1.8597ωe, Δω/ωmid=10.9%. 相似文献
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Chen-Yang Liu 《Physics letters. A》2008,372(31):5198-5202
Photonic crystals (PCs) have many potential applications because of their ability to control light-wave propagation. We have investigated the tunable absolute bandgap in a two-dimensional anisotropic photonic crystal structures modulated by a nematic liquid crystal. The PC structure composed of an anisotropic-dielectric cylinder in the liquid crystal medium is studied by solving Maxwell's equations using the plane wave expansion method. The photonic band structures are found to exhibit absolute bandgaps for the square and triangular lattices. Numerical simulations show that the absolute bandgaps can be continuously tuned in the square and triangular lattices consisting of anisotropic-dielectric cylinders by infiltrating nematic liquid crystals. Such a mechanism of bandgap adjustment should open up a new application for designing components in photonic integrated circuits. 相似文献
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A novel design of a tunable terahertz switch and band-pass filter using liquid-crystal-filled photonic crystal waveguide is demonstrated. The effects of magnetic field on the photonic bandgaps and transmitting properties of a THz wave are investigated by using the plane wave expansion method and finite difference time domain method. The efficient photonic bandgap tuning is predicted such that the two-dimensional liquid-crystal-filled photonie crystal waveguide can serve as a switch and continuously tunable band-pass filter with controlling of the magnetic field. 相似文献
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Liwei Zhang Guiqiang Du Yewen Zhang 《Applied Physics A: Materials Science & Processing》2012,109(4):851-856
We present a theoretical investigation into the energy transport and transient wave propagation in metamaterial tunneling structures consisting of ??-negative (ENG) and ??-negative (MNG) materials. It is proved that a conjugated matched ENG/MNG bilayer and a (zero-index-material doped) photonic crystal heterostructure can work as a sub-wavelength resonator at tunneling frequency. The tunneling modes need a certain time to achieve the steady state and the charge up characteristic time increases (nearly) exponentially with the thickness of the structures. Under the steady state, the wave in the single-negative-material structures is not evanescent, but a hybrid of a traveling wave and a reactive standing wave. The phase difference between the electric field and the magnetic field varies with the position and time. The investigation of transient wave propagation in the metamaterial tunneling structures will help us to understand the interaction process between wave and metamaterial and to design special functional apparatus. 相似文献
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A theoretical investigation of a novel type of optical fiber is presented. The operation of the fiber relies entirely on wave guidance through the photonic bandgap effect and not on total internal reflection, thereby distinguishing that fiber from all other known fibers, including recently studied photonic crystal fibers. The novel fiber has a central low-index core region and a cladding consisting of a silica background material with air holes situated within a honeycomb lattice structure. We show the existence of photonic bandgaps for the silica-air cladding structure and demonstrate how light can be guided at the central low-index core region for a well-defined frequency that falls inside the photonic bandgap region of the cladding structure. 相似文献
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采用平面波法(PWM)计算一维光子晶体的带隙结构。分别就构造一维光子晶体结构的高低折射膜层的介电常数及填充比(高折射膜层的厚度与晶体周期长度的比值)对禁带带隙宽度的影响作出分析。通过最小二乘曲线和曲面拟合得到带宽与介电常数或带宽与填充比的函数关系图,以确定最佳的禁带带宽,从而设计一维光子晶体的周期结构。对高低折射膜层为GaAs/空气组成的一维光子晶体,介电常数比约为13/1,当填充比为0.16时,计算得禁带带宽为0.2564×2πc/Λ,禁带的中心频率为0.3478×2πc/Λ,与实验数据吻合。 相似文献
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J. Cos J. Ferré-Borrull J. Pallarès L. F. Marsal 《Applied physics. B, Lasers and optics》2010,100(4):833-839
We present a theoretical study on two-dimensional photonic crystals composed of silicon and the E7 liquid crystal. We analyze
how the optical axis orientation of the liquid crystal influences the photonic bands and bandgaps, for the case when the Maxwell
equations can be decoupled into the TE and TM modes. We consider two different structures, a triangular lattice of E7 liquid
crystal cylinders in a silicon background and a triangular lattice of silicon cylinders in an E7 liquid crystal background.
The effect of the liquid crystal anisotropy on the geometry of the irreducible Brillouin zone allows us to propose a simplified
way to calculate the photonic bandgaps. Results show that the bandgap width and center frequency have a 60° periodicity for
both structures. Using the plane-wave expansion method, we determined the maximum bandgap and the optimal radius of the cylinders
for each structure. Finally, for the second structure, we propose an optical switch with a 50% duty cycle. These structures
can be applied to design tunable photonic devices. 相似文献
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异质镜像光子晶体的光子带隙研究 总被引:1,自引:0,他引:1
对异质镜像结构光子晶体(ABCCBA)N进行了研究。首先,利用一维介电体系中处理光传播的方法--传输矩阵法,详细推导了异质镜像光子晶体透射率的计算公式;然后,采用Matlab软件编程仿真并分析了光子带隙形成与镜像周期数目、光子带隙数目与光子晶体薄层厚度、光子带隙位置与入射角大小等的关系。结果表明:光子带隙的形成及变化主要受光子晶体薄层厚度及入射角大小变化的影响。通过改变影响光子晶体光子带隙的参数,可得到不同频段的光子带隙,用来制作高质量反射镜、滤波器和发光二极管等。 相似文献
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Wide angularly isotropic photonic bandgaps obtained from two-dimensional photonic crystals with Archimedean-like tilings 总被引:1,自引:0,他引:1
We present a theoretical study of new two-dimensional photonic crystals based on Archimedean-like tilings. Three structures are considered: a square lattice with a 4-atom unit cell and triangular lattices with 7- and 13-atom unit cells. A 12-fold local rotational symmetry is obtained for the triangular lattices and is approached for the square lattice. Wide photonic bandgaps can then be achieved, with very weak bandwidth dependence (~1%) on the wave-propagation direction. The complete bandgap frequency is shown to depend on the atomic bond length and not on the crystal period. This new class of periodic photonic crystals is a simple and attractive alternative to photonic quasi crystals. 相似文献