位相光栅偏振特性的耦合波分析

基于麦克斯韦方程组和电磁场的边界连续条件，本文导出了位相光栅的严格的矢量耦合波衍射方程，指出了各级次衍射波之间存厢互耦合作用，并分析了光栅的偏振效应，得到光栅在不同偏振方式下的衍射特性，实验测试结果验证了理论分析和正确性。     

严格耦合波法计算闪耀光栅衍射效率

针对一般标量近似算法精度不高的问题,提出采用S矩阵的严格耦合波的方法计算光栅衍射效率.通过建立完整的闪耀光栅理论模型,对各分层电磁场进行傅里叶级数展开,采用散射矩阵方法求解各谐波系数,完成衍射效率计算.该方法已应用到红外光栅TE和TM 2种模式衍射效率的计算.分析了散射矩阵解决数值运算不稳定的原因,通过与标量近似计算方法进行比较,说明红外光栅衍射偏振特性.     

用耦合波方法研究取样光栅的衍射特性

介绍了利用耦合波理论编写计算光栅衍射特性程序的基本思想和主要步骤.利用编写的程序计算并分析了一种用于激光取样光栅TE波和TM波的衍射特性.     

用耦合波方法研究取样光栅的衍射特性

 介绍了利用耦合波理论编写计算光栅衍射特性程序的基本思想和主要步骤。利用编写的程序计算并分析了一种用于激光取样光栅TE波和TM波的衍射特性。     

亚波长闪耀光栅矢量衍射效率计算

将矢量衍射数值算法—严格耦合波分析用于精确计算亚波长闪耀光栅的衍射效率,并分析其衍射特性。建立了闪耀光栅的电磁介质模型,并将楔形不规则结构简化为多层矩形光栅结构,通过电磁场的介质分布建立严格耦合波方程。根据边界条件求解出各层的电磁场分布,再通过增透矩阵方法将各层电磁场依次迭代,求解出了整个结构的衍射效率。计算分析显示,对闪耀角为11.3°、周期为500 nm的金属铝闪耀光栅可以得到高于90%的衍射效率和相应的闪耀级次。实验表明这种矢量衍射数值算法具有较高的准确性,可以推广应用于高致密刻线复杂光栅的衍射计算分析。     

基于严格耦合波理论的宽光谱金属介质膜光栅衍射特性分析

基于严格耦合波理论建立了金属介质膜光栅的衍射机理模型,给出了TE模式金属介质膜光栅衍射效率的表达式.以-1级衍射效率和工作带宽为评价函数,对金属介质膜光栅的表面浮雕结构进行了优化设计.对于800 nm和1053 nm为中心的TE波,设计的金属介质膜光栅-1级衍射效率优于97%的工作带宽分别达到130 nm和150 nm,最后讨论了设计的宽光谱高衍射效率金属介质膜光栅的制备工艺容差.此研究对于提高脉宽压缩光栅的性能具有重要的意义. 关键词： 衍射效率 金属介质膜光栅 严格耦合波理论     

红外波段高效率低偏振相关损耗光栅的设计

衍射效率高、偏振相关损耗低的衍射光栅是集成波分复用/解复用器件的一种核心元件,在光通信中具有很重要的应用价值。通过利用严格的耦合波理论计算光栅衍射效率的方法,分别编制出了计算TE波和TM波的衍射效率程序。通过改变光栅的面形来进行计算,最终得到了衍射效率高和偏振相关损耗小的光栅面形。     

TM模场入射到金属光栅的表面增强喇曼散射计算分析

以纳米量级金属履带矩形光栅为模型,研究了表面增强喇曼散射的特性.针对TM模的入射光,采用严格的耦合波原理对金属表面的衍射场进行了分析,并用数值计算方法讨论了光栅深度、光栅占空比等参量对金属表面增强的影响以及增强因子随光栅深度的变化关系.结果显示：当入射光波长为700 nm、入射角度为10°、光栅周期p=600 nm、 光栅深度d=37.5 nm、占空比为1/3时,获得最大增强,增强因子G达104倍.     

亚微米光栅零级衍射特性的数值研究

用耦合波理论分析了亚微米光栅对光波场的衍射作用,给出了在TE和TM偏振入射条件下矩阵形式的耦合波方程,研究了光栅在TE偏振入射条件下可见光波段内的反射和透射零级衍射特性。亚微米光栅零级衍射效率是波长、偏振和入射角的函数,在不同照明、观察和光栅参数条件下,光栅零级衍射具有非常复杂的光谱结构,经过适当的优化光栅参数,零级衍射具有许多独特的衍射特性,在许多应用领域具有广泛的应用前景。     

矩形光栅的衍射特性

本文采用严格的一阶耦合波理论,对矩形光栅的衍射特性进行了分析,给出了TE模和TM模同时具有很高的衍射效率时的光栅结构。计算表明:只有在满足Bragg衍射条件时,TE模和TM模才能达到峰值衍射效率。为了验证理论与编制程序的正确性,将计算结果与已有的资料进行了比较.     

位相光栅的严格模式理论及其全反射特性

用严格的模式理论研究了位相光栅中的电磁场分布和各衍射级次的衍射效率.用分段解析函数来表达本征函数，而不采用无穷级数的方法.利用稳定、快速和精度高的递推公式来计算反射透射阵和振幅系数阵，从而能处理任意多台阶的位相光栅.数值计算结果表明，存在全反射.也讨论了全反射的条件和物理机制. 关键词：     

基于格林函数法研究金属线栅在太赫兹波段的散射特性

本文运用格林函数法分析金属线栅在太赫兹(THz)波段的散射特性, 研究金属线栅的衍射效应对其传输特性的影响. 研究结果表明, 在零级衍射区入射电磁波的透过振幅随a/λ的增大单调增加, 在零级衍射极限处透过振幅达到最大值. 过渡区的临界频率处, 由于衍射效应的加强, 出现入射电磁波透过曲线的振荡. 衍射区受到衍射效应的影响入射电磁波透射振幅曲线总体下降, 并随a/λ的增大单调减少. 与微波传输线方法相比, 该方法摆脱了入射电磁波的波长需大于线栅常数且要求线栅的厚度远远小于金属线的宽度的限制, 能准确的分析系统的电磁场的分布特性, 更具普适性. 关键词： 金属线栅 太赫兹波 散射 格林函数法     

Electromagnetic Diffraction Analysis of 2-D Antireflective Subwavelength Grating with Coned Profile

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Electromagnetic Diffraction Analysis of 2-D Antireflective Subwavelength Grating with Coned Profile

2D subwavelength multilevel (2-, 4-, 8-, etc. levels) columned stairstep grating with coned spatial profile has been designed to reduce reflection. In this paper, the rigorous coupled-wave theory is employed to analyze the electromagnetic diffraction property of the columned stairstep grid grating. The structure is shown to achieve extremely low reflectance over a wide field of view and a wide light wave band.     

Shape resonances in nested diffraction gratings

The diffraction problem of a plane wave impinging on a grating formed by nested cavities is solved by means of the modal method, for s and p polarization modes. The cavities are formed by perfectly conducting sheets that describe rectangular profiles. The electromagnetic response of the grating is analyzed, paying particular attention to the generation of resonances within the structure. The dependence of the resonances on the geometrical parameters of the grating is studied, and results of far and near field are shown. The results are checked and compared with those available in the literature for certain limit cases.     

各向异性介质浮雕光栅体内光波场的传输

分析了各向异性介质光栅体内光波场的空间分布,并将RTRA递推算法推向了各向异性介质内光波场的传输.数值计算表明,光波场光强的空间分布随透射深度的变化而变化,各向异性介质光栅体内光波场的空间分布相对各向同性介质要均匀,光栅材料的性质参数和光束的入射参数对光波场光强的空间分布有较大的影响等.     

Calculation and optimization of parameters of deep groove gratings with multilayer dielectric coating for compression of high-power laser pulses

The method of calculating the electromagnetic wave field diffracted by a holographic grating with a multilayer dielectric coating is developed. The method consists of the representation of the field inside dielectric layers in the form of a plane-wave expansion for weakly damped harmonics and an expansion over functions of the concomitant coordinate system for strongly damped orders. This modification of the method allows calculation of the diffraction efficiency and the electric field strength for the deep groove gratings. It is shown that a diffraction element that possess high efficiency and radiation strength can be obtained even when the profile of the dielectric layers flattens with an increase in the distance from the grating’s metallic layer.     

Grating-assisted generation of 2D surface plasmon interference patterns for nanoscale photolithography

Generation of 2D surface plasmon interference patterns using a 3D metal-dielectric diffraction structure is studied. The potential application field is surface plasmon interference nanolithography aimed at fabrication of 3D periodic structures. The considered structure consists of a 3D dielectric diffraction grating with a metal film applied in the substrate region. The diffraction grating is designed to transform the incident wave into a set of surface plasmons that generate 2D interference pattern underneath the metal film. The configuration of the interference patterns is analyzed theoretically. It is shown by simulations within the rigorous electromagnetic theory that high-contrast interference patterns with the period 2.5-3.5 times smaller than the incident wave length can be produced. The configuration of the calculated patterns coincides with theoretically estimated ones. At the interference maxima electric field intensity exceeds incident wave intensity by an order of magnitude. The ways to control the form and period of the interference pattern by changing polarization and length of the incident wave are presented.     

Digital volume gratings

An optical element constructed by stacking a set of binary-phase grating sheets can simulate the functions of optically recorded volume gratings. Our electromagnetic numerical study also shows that if one of the grating sheets is replaced by another one with different grating period, power spectrum of the diffracted wave changes completely with extra diffraction orders. This property will claim strong advantage in security document applications. Analysis of alignment error reveals interesting phenomena concerning to how misalignment affects diffraction efficiency.