二维正方格子磁性光子晶体的带隙结构

采用平面波展开的方法计算了正方格子二维磁性光子晶体(MPC)的光子带隙结构.散射子的形状分别为：长方形，正方形，六角形和圆形.通过调节磁导率，填充率和散射子的旋转角度，找到了MPC各种结构的最大的绝对带隙宽高比ω_R.研究发现：随着磁导率的增加，MPC绝对带隙中心频率ω_g单调减小，绝对带隙宽度Δω和其宽高比ω_R可能不同时达到最大值.而随着填充率或者散射子旋转角的增加，基本不改变ω_g的大小，各种结构的Δω和ω_R同时达到最大值. 关键词： 磁性光子晶体 光子带隙结构     

波状结构二维光子晶体负折射现象的研究

结合波状结构二维(2D)光子晶体(PC)与入射介质两者的等频面结构分析了PC内部的负折射现象，采用时域有限差分(FDTD)方法模拟了高斯光束在波状结构2DPC内的负折射，分别得到了折射角/入射角以及折射角/入射波长之间的关系曲线，当入射角为45°，入射波段在1485—1530nm区域时，波状结构2DPC的负折射角与入射波长近似呈线性变化关系，并带有明显的PC超棱镜效应，采用端面投影方法对波状结构2DPC的入射端面和出射端面进行处理，改善了负折射时的透过率. 关键词： 光子晶体 负折射 等频面     

Photonic band structures of two-dimensional photonic crystals with deformed lattices

Using the plane-wave expansion method, we have calculated and analysed the changes of photonic band structures arising from two kinds of deformed lattices, including the stretching and shrinking of lattices. The square lattice with square air holes and the triangular lattice with circular air holes are both studied. Calculated results show that the change of lattice size in some special ranges can enlarge the band gap, which depends strongly on the filling factor of air holes in photonic crystals; and besides, the asymmetric band edges will appear with the broken symmetry of lattices.     

2维光子晶体中的掺杂效应数值研究

把平面波展开方法(PWM)用于2维光子晶体掺杂情况下透射特性的研究,计算得到了粗细不同的空气柱掺杂、相同半径不同介质柱掺杂、不同柱体形状掺杂情况下2维光子晶体的透射系数与入射光频率的关系曲线。结果表明2维光子晶体的禁带的宽度、位置、透过率与掺杂体半径、掺杂体介电常数、掺杂体柱体几何形状等因素有关,掺杂因素相差越大透射曲线变化越明显,特别是损耗介质的掺入更使得禁带可调要素增加。     

2维光子晶体中的掺杂效应数值研究

 把平面波展开方法(PWM)用于2维光子晶体掺杂情况下透射特性的研究,计算得到了粗细不同的空气柱掺杂、相同半径不同介质柱掺杂、不同柱体形状掺杂情况下2维光子晶体的透射系数与入射光频率的关系曲线。结果表明2维光子晶体的禁带的宽度、位置、透过率与掺杂体半径、掺杂体介电常数、掺杂体柱体几何形状等因素有关,掺杂因素相差越大透射曲线变化越明显,特别是损耗介质的掺入更使得禁带可调要素增加。     

Numerical study on characteristic of two-dimensional metal/dielectric photonic crystals

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.     

波状结构二维光子晶体的自准直特性及亚波长成像的研究

利用平面波展开方法计算了波状结构二维光子晶体(2DPC)的等频面，对等频面内矩形轮廓的等频线进行研究，提出了波状结构2DPC的自准直特性，运用时域有限差分(FDTD)方法模拟了波状结构2DPC在不同入射角情况下对所入射高斯光束的自准直作用.将波状结构2DPC的自准直特性运用到近场亚波长成像，模拟了波状结构2DPC的自准直亚波长成像效果，单光源的成像分辨率达到0.28λ，且随着光源逐渐远离近场范围而降低. 关键词： 光子晶体 自准直 等频面 亚波长成像     

Modelling and design of complete photonic band gaps in two-dimensional photonic crystals

In this paper, we investigate the existence and variation of complete photonic band gap size with the introduction of asymmetry in the constituent dielectric rods with honeycomb lattices in two-dimensional photonic crystals (PhC) using the plane-wave expansion (PWE) method. Two examples, one consisting of elliptical rods and the other comprising of rectangular rods in honeycomb lattices are considered with a view to estimate the design parameters for maximizing the complete photonic band gap. Further, it has been shown that complete photonic band gap size changes with the variation in the orientation angle of the constituent dielectric rods.      

空气环型二维光子晶体完全带隙特性研究

采用平面波展开法, 系统研究了空气环型二维光子晶体的完全光子带隙随结构参数变化而改变的规律, 并将其与普通的空气孔型和介质柱型二维光子晶体的完全带隙进行了比较. 研究表明: 空气环型二维光子晶体不仅可以获得更宽的完全带隙, 而且, 当介质折射率较低时, 其可以获得普通空气孔型和介质柱型二维光子晶体在低折射率条件下所无法获得的完全带隙. 关键词： 空气环型二维光子晶体 完全带隙 平面波展开法     

二维蜂窝格子光子晶体的远场成像特性及界面对成像质量的影响

利用有限时域差分法研究了一种二维蜂窝格子光子晶体的远场亚波长成像特性，发现和折射率为-1时的负折射成像规律符合得很好.但是由于晶格结构本身的特性，入射光以大角度入射时，这种结构的耦合效率很低，影响了像的强度和质量.通过适当改变界面上介质柱的半径的方法可以提高耦合效率，进而有效提高成像的质量和强度.     

Designing analysis of the polarization beam splitter in two communication bands based on a gold-filled dual-core photonic crystal fiber

We design a novel kind of polarization beam splitter based on a gold-filled dual-core photonic crystal fiber （DC-PCF）. Owing to filling with two gold wires in this DC-PCF, its coupling characteristics can be changed greatly by the second-order surface plasmon polariton （SPP） and the resonant coupling between the surface plasmon modes and the fiber-core guided modes can enhance the directional power transfer in the two fiber-cores. Numerical results by using the finite element method show the extinction ratio at the wavethlengths of 1.327 μm and 1.55 μm can reach -58 dB and -60 dB and the bandwidths as the extinction ratio better than -12 dB are about 54 nm and 47 nm, respectively. Compared with the gold-unfilled DC-PCF, a 1.746-mm-long gold-filled DC-PCF is better applied to the polarization beam splitter in the two communication bands of λ = 1.327 μm and 1.55 μm.     

二维圆柱形光子晶体的完全禁带研究

用平面波展开法研究了二维圆柱形光子晶体的完全禁带与填充比、介电常数比之间的关系. 研究发现,并非介电常数比越大,完全禁带宽度就越大,而是有一个峰值. 关键词： 二维光子晶体 完全禁带 平面波展开法     

Frequency bands of negative refraction in finite one-dimensional photonic crystals

We have discussed theoretically the negative refraction in finite one-dimensional (1D) photonic crystals (PCs) composed of alternative layers with high index contrast. The frequency bands of negative refraction are obtained with the help of the photonic band structure, the group velocity and the power transmittance, which are all obtained in analytical expression. There shows negative transverse position shift at the endface when negative refraction occurs, which is analysed in detail.     

FDTD法对二维正方格子光子晶体带隙的数值计算

通过optiFDTD模拟软件对二维椭圆柱构造的正方格子光子晶体的禁带特性进行了数值模拟。分别研究了在空气中椭圆介质(Ge,Si,GaAs)柱和在介质(Ge,Si,GaAs)中椭圆空气柱构造的二维正方格子光子晶体中椭圆柱的横轴半径和纵轴半径的大小,以及椭圆柱的不同旋转角度对光子禁带的影响;并计算出了在上述两种情况下的空气和介质中的最优结构参数。     

具有镜像对称结构的一维光子晶体的透射谱

计算了具有镜像对称性结构的一维光子晶体的透射谱.在光子晶体的禁带中得到了多个完全透射峰.用数学归纳法得到了简单的迭代关系式用以计算多个完全透射峰的频率.只要结构具有镜像对称性，中心透射峰总是存在，而其他透射峰则依赖于缺陷的位置和折射率.适当选择对称结构，可以得到一个近完全透射带. 关键词： 光子晶体 缺陷模 透射谱     

旋转对二维正方晶格介质柱内空结构光子晶体禁带的影响

采用平面波展开的方法计算了三种旋转操作下二维正方晶格各向异性材料(Te)介质柱内空结构光子晶体TE,TM模式能带.讨论了三种旋转操作对TE,TM模式带隙及完全光子禁带的影响.发现TM模式高频带隙与结构的旋转对称性有着密切的关系.而TE模式的带隙不仅受到晶体旋转对称性的影响同时也受到介质在x-y平面分布情况的影响.     

Far infrared Faraday rotation effect in one-dimensional microcavity type magnetic photonic crystals

The far infrared transmittances and Faraday rotation effect in one-dimensional photonic crystals that contain magnetic microcavities are calculated with the transfer matrix method. The different stacking sequences of dielectric layers in the magnetic photonic crystal are considered in this paper, and the linewidths of transmission peaks and localised light of the photonic crystals are discussed. The enhancement of Faraday rotation is presented in the magnetic photonic crystals, and the largest rotation angle at the frequency of the transmission peak is 29 °mm⁻¹, which is larger than previous results.     

旋转对二维正方晶格介质柱内空结构光子晶体禁带的影响

采用平面波展开的方法计算了三种旋转操作下二维正方晶格各向异性材料(Te)介质柱内空结构光子晶体TE,TM模式能带.讨论了三种旋转操作对TE,TM模式带隙及完全光子禁带的影响.发现TM模式高频带隙与结构的旋转对称性有着密切的关系.而TE模式的带隙不仅受到晶体旋转对称性的影响同时也受到介质在x-y平面分布情况的影响. 关键词： 二维光子晶体 内空结构 旋转操作 光子带隙     

Optimize design super collimation in square lattice two-dimensional photonic crystals

The plane wave expansion (PWE) method was used to get the three-dimensional band diagram and equifrequency surface (EFS). From the EFS the maximum flatness half width (MFHW) and its position were got. The relation between MFHW and filling fraction P_f, dielectric ratio ε_b/ε_a were given in order to get the optimal structure we employ in this paper. Then the maximum super collimation was given by beam propagation method (BPM).     

Graphite格子光子晶体带隙的数值模拟

采用平面波展开法模拟计算了由锗圆柱构成的Graphite格子二维光子晶体的带隙结构,发现由空气背景中的介质柱构成的二维Graphite格子结构的光子晶体具有完全光子带隙,并得到了使完全带隙最大化的结构参数。数值计算结果表明,Graphite结构二维光子晶体在填充比从f=0.058到f=0.605连续变化的很大范围内都有完全带隙出现,在低能区出现了Δ=0.053(ωa/2πc)的较大带隙。