共查询到20条相似文献,搜索用时 8 毫秒
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利用严格傅里叶模式理论研究了不同基底折射率、入射角度、归一化周期、归一化沟槽深度对正弦型光栅微结构衍射效率的影响,并分析了该光栅的衍射特性.基于标量衍射理论和等效介质理论,分别计算了光栅周期远远大于和远远小于入射波长时,正弦型光栅的衍射效率,并与傅里叶模式理论的计算结果进行比较,分析标量衍射理论和等效介质理论的有效性.结果表明:在垂直入射条件下,当光栅基质材料折射率为1.5时,标量衍射理论在光栅归一化周期大于5时,能够准确计算光栅衍射效率,误差小于3%;当基底折射率增大到3.42时,只有在光栅归一化周期大于10时,标量衍射理论才有效,误差小于5%;当正弦型光栅透射光中只有0级衍射光传播时,等效介质理论能够准确计算其透射率;随着入射角度的增大,标量衍射理论和等效介质理论的有效性都不同程度地降低. 相似文献
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We fabricated a two-dimensional subwavelength grating (SWG) on a polymethyl methacrylate (PMMA) film using a molding technique. A method of fabricating SWGs with high accuracy using a replica technique in an atmospheric environment was proposed. The SWG consisted of tapered gratings with a 200 nm period and a 200 nm deep groove. The reflectivity at wavelengths from 400 nm to 800 nm was measured and compared with the results calculated on the basis of rigorous coupled-wave analysis. At these wavelengths, the reflectivity decreased to approximately half that of the PMMA film. 相似文献
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Various optical elements with subwavelength structured surfaces have been developed. The periods of the subwavelength structures are too short to generate diffracted light waves. But the structures are equivalent to refractive index materials with form birefringence. Many new optical elements are realized using the artificial refractive indices of these subwavelength structures. Some typical elements are described here in the passive element regime, and fabrication methods of the elements are explained. 相似文献
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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. 相似文献
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The finite-difference time-domain (FDTD) method is applied to the numerical evaluation of diffraction from a binary relief grating with subwavelength structures. It is demonstrated numerically that the binary relief grating made of isotropic materials works as a polarization selective optical device. It is further shown that the polarization effects depend on the arrangements of subwavelength structures. 相似文献
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Electromagnetic Diffraction Analysis of 2-D Antireflective Subwavelength Grating with Coned Profile 总被引:2,自引:0,他引:2
1 Introduction Itiswellknownthatconventionalmethodsof producingextremelybroadbandantireflectivesurfacesarelimitedintheinfraredregion ,becauseofthelimitednumberofthin filmcoatingmaterialsavailableforusetoday .Subwavelengthsurface relief gratingshavebeenr… 相似文献
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A new model is proposed to explain the physical mechanism of the extraordinary transmission enhancement in subwavelength metallic grating. The extraordinary transmission enhancement is described by the co-operation of Fabry-Perot-like (FPL) resonance and the surface plasmon polariton (SPP) resonance. The rigorous coupled-wave analysis (RCWA) and the finite difference time domain (FDTD) method are employed to illustrate the model by calculating the transmission and the field distributions in the subwavelength metallic grating, respectively. And the numerical calculations show that transmission enhancement is achieved when the coupling resonance of the incident light, the surface plasmon polariton mode and the Fabry-Perot-Like mode is happened, which are in good agreement with the proposed model. 相似文献
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结合有效介质理论和薄膜光学的抗反射设计方法,设计了基于0.65μm工作波长的亚波长金属偏振分束光栅,给出了光栅的优化设计参数,采用严格耦合波理论分析了光栅的偏振分束特性.结果表明,亚波长金属光栅对TE偏振表现为金属膜特性,具有高反射,对TM偏振表现为介质膜特性,具有高透射,在-30°<θ<30°的大入射角范围和0.47μm<λ<0.80μm的宽入射波谱内,该光栅的透射光和反射光均具有高偏振消光比和低插入损耗的特点.
关键词:
亚波长金属偏振分束光栅
有效介质理论
薄膜光学
严格耦合波理论 相似文献
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Gratings with subwavelength groove depth and period are frequently used in optics for various purposes. The polarization dependent diffraction characteristics of subwavelength (high frequency) gratings can only be calculated by solving Maxwell’s equations of electromagnetism. In this paper, we calculate the classical diffraction characteristics of subwavelength conducting gratings numerically, using a new high accuracy version of nonstandard finite-difference time-domain (NS-FDTD) algorithm. For the purpose of analysis, we employ a gold sinusoidal grating with light incident at a large angle. We have compared high accuracy NS-FDTD simulation results with those obtained from standard finite-difference time-domain (S-FDTD), and the finite element method (FEM) simulations. 相似文献
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A binary subwavelength structure for multilevel phase modulation can be designed by our previously proposed deterministic
design method without iterative optimization method. To use our design technique in various applications of a computer generated
hologram (CGH) like an array illuminator, beam-shaping, signal processing, and so on, an image quality of a reconstructed
image from a CGH has become much more important. In this paper, we verify the image quality of a reconstructed image from
a CGH designed by our method in terms of the modulation transfer function (MTF) and the spatial resolution. Simulation results
show that our technique can theoretically achieve a MTF of more than 99% over a wide range and a spatial resolution of less
than 9.66μm. 相似文献
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负折射率介质层中光波的相位和传输特性研究 总被引:13,自引:0,他引:13
针对在理解负折射率材料中光波的传播特性时相位的特殊性质 ,详细分析推证了负折射率介质中折射率、波矢k的大小和方向、空间坐标系以及波相相位互之间的关系。分析结果表明负折射率介质层中的波矢k的反常取向是由于其标量值为负 ;在统一的坐标系下 ,由该标量值参与数值计算和分析 ,k则由标量值和单位矢量k0 (k0 >0 )共同决定 ,而不必再考虑左、右手系的区别。在此基础上依据电磁场理论推导了光波在负折射率介质层中的传输矩阵 ,用以分析含有负折射率介质层的复杂薄膜系统的光学性质。初步计算结果显示含有负折射率介质层的膜系对TE和TM波的光谱特性都有显著改变 相似文献
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报道了一种用高频CO2激光脉冲在普通通信光纤包层边缘单侧写入的新型长周期光纤光栅。研究发现,这种长周期光纤光栅的折射率变化主要发生在光纤包层区域,而纤芯的折射率变化较小;同时该光栅的附加损耗低于0.5 dB。进一步折射率特性实验研究表明,由于其特殊的折变结构,这种光栅具有较高的外界环境灵敏度,当外界折射率在1.41~1.45范围内变化时,其谐振波长漂移量高达15.52 nm,比实验测得的用传统方法写入的长周期光纤光栅谐振波长漂移量高出近3倍,这种光栅结构在光纤传感中将具有重要的应用。 相似文献