共查询到20条相似文献,搜索用时 31 毫秒
1.
利用四个Au纳米棒组成的类矩形纳米棒四聚体结构设计了一种基于偏振态控制的光开关,并采用有限元法研究了该结构对入射光偏振态的响应特性.研究发现,该结构的透射光谱对入射光的偏振方向具有很强的依赖性,当入射光的偏振角度变化π/2时,其特征峰的开关比分别能达到27.81dB和21.65dB.分析表明,该结构的开关效应主要由不同偏振态下所导致的水平双纳米棒和竖直双纳米棒之间的近场耦合强度不同而实现,该结构透射系数与偏振角度的关系服从Malus law.此外,通过改变类矩形纳米棒阵列结构参数,研究了结构参数对其光开关响应特性的影响.在此基础上,通过改变阵列的周期参数,研究了入射光水平偏振和垂直偏振下周期参数对单元结构透射光谱的影响.该研究结果能够为可调谐双波长偏振光开关的设计提供理论依据. 相似文献
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基于电磁局域谐振的路谐振理论, 将集总LC器件加载到工字形周期阵列中, 设计了一种新型频率选择表面极化分离结构. 利用等效电路法分析了不同极化时该结构的作用机制, 并采用全波分析法研究了极化方式、入射角度和集总参数对其传输特性的影响.结果表明: 所设计的结构在6.37 GHz附近具有良好的极化分离特性; 在0°–40°扫描范围内, 横电(TE) 和横磁(TM) 极化下结构传输特性均保持稳定; 通过调控集总元件LC值, 该结构在保持 TE极化方向传输特性不变的同时, 可以实现对TM传输特性的独立调节, 使设计更加灵活.该结构为极化分离器以及极化波产生器的设计提供了借鉴.
关键词:
频率选择表面
极化分离器
集总电容
集总电感 相似文献
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A. L. Sokolov 《Optics and Spectroscopy》2003,95(5):814-818
A range of questions regarding the calculation of the spatial polarization structure of laser radiation in optical systems is considered. It is shown that polarization aberrations in such systems lead to a distortion of the initial polarization structure. Requirements for an optical system intended for the transmission of the polarization structure of laser radiation and methods for the compensation of polarization aberrations are discussed. 相似文献
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The many-body optical gain in Li:CdZnO/MgZnO quantum well (QW) structures with spontaneous polarization and piezoelectric polarization, and ferroelectric dipole moment is investigated by using the non-Markovian gain model with many-body effects. The CdZnO/MgZnO QW structure with high Cd composition is found to have smaller optical gain because the strain-induced piezoelectric polarization and the spontaneous polarization in the well increase with the inclusion of Cd. The internal field is reduced due to the additional polarization by Li in the CdZnO/MgZnO QW structure. These results show that Li:CdZnO-based QW lasers are promising candidates for optoelectric applications in visible and UV regions. 相似文献
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金属线栅偏振器是一种新兴的基于微纳结构的光学偏振器件, 体积小、性能高、易集成.但在紫外和可见光波段, 通过缩小线栅的特征尺寸来提高消光比的方法已经受到纳米制作工艺的限制, 因此需要新的结构来提高其偏振特性.双层金属线栅结构仅在特定波段上提高 器件的偏振特性. 在此基础上, 提出一种间距可调谐的金属线栅偏振器结构, 通过调谐两层金属线栅之间的距离来确保偏振器极高的消光比和很强的透过率. 利用VirtualLab软件的傅里叶模式方法, 计算了可调谐型金属线栅偏振的透过率和消光比. 数值仿真结果表明, 双层可调谐型金属线栅结构在整个紫外、 可见光波段极大地提高了透射光的消光比和透过率.
关键词:
线栅偏振器
可调谐结构
消光比
压电陶瓷 相似文献
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《Physica E: Low-dimensional Systems and Nanostructures》2011,43(10):2652-2654
The CdZnO/ZnMgO QW structure with high Cd composition is found to have smaller optical gain because the strain-induced piezoelectric polarization and the spontaneous polarization in the well increase with the inclusion of Cd. The internal field is reduced due to the additional polarization of opposite direction by Li in the CdZnO/ZnMgO QW structure. These results show that Li:CdZnO-based QW lasers are promising candidates for optoelectric applications in visible and UV regions. 相似文献
10.
Johnson RD Chapon LC Khalyavin DD Manuel P Radaelli PG Martin C 《Physical review letters》2012,108(6):067201
In rhombohedral CaMn7O12, an improper ferroelectric polarization of magnitude 2870 μC m(-2) is induced by an incommensurate helical magnetic structure that evolves below T(N1)=90 K. The electric polarization was found to be constrained to the high symmetry threefold rotation axis of the crystal structure, perpendicular to the in-plane rotation of the magnetic moments. The multiferroicity is explained by the ferroaxial coupling mechanism, which in CaMn7O12 gives rise to the largest magnetically induced, electric polarization measured to date. 相似文献
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We studied the characteristics of a circular metallic grating illuminated by broadband radial and azimuthal polarizations. We demonstrated that this scenario is the cylindrical analogue of a one-dimensional Cartesian grating illuminated by TM and TE polarizations. We measured the transmission spectra of this structure and observed strong polarization selectivity and, specifically, a resonance for radial polarization excitation, indicating a strong coupling to surface plasmons. The structure may be attractive for applications where pure radial polarization is needed, such as tight focusing, material processing, and particle trapping. 相似文献
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Gen Luo 《Waves in Random and Complex Media》2017,27(3):513-525
In this article, the turbulence structure generated by a propeller is simulated with the computational fluid dynamics (CFD) software FLUENT. With the method of moments, the backscattering radar cross sections (RCS) of the turbulence structure are calculated. The scattering results can reflect the turbulent intensity of the wave profiles. For the wake turbulence with low rotating speed, the scattering intensity of HH polarization is much smaller than VV polarization at large incident angles. When the turbulence becomes stronger with high rotating speed, the scattering intensity of HH polarization also becomes stronger at large incident angles, which is almost the same with VV polarization. And also, the bistatic scattering of the turbulence structure has the similar situation. These scattering results indicate that the turbulence structure can also give rise to an anomaly compared with traditional sea surface. The study of electromagnetic (EM) scattering from turbulence structure generated by the propeller can help in better understanding of the scattering from different kinds of waves and provide more bases to explain the anomalies of EM scattering from sea surfaces. 相似文献
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N. N. Matveev N. Yu. Evsikova N. S. Kamalova N. I. Korotkikh 《Bulletin of the Russian Academy of Sciences: Physics》2013,77(8):1076-1077
Polarization phenomena caused by the presence of temperature gradients in a biopolymer such as wood are considered. It is shown that cellulose crystallites are centers of polarization in the fiber-forming part of the considered biocomposite. The relation for elementary polarization is obtained. It is proposed that the supermolecular structure of cellulose in samples of wood be studied by measuring the electric field characteristics of a thermal polarization nature. 相似文献
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We present a novel method for forming linearly polarized axially symmetric beams with various polarization orders that is based on computer-generated space-variant subwavelength gratings. We introduce and experimentally demonstrate that our space-variant polarization state manipulations are accompanied by a phase modification of a helical structure that results from the Pancharatnam-Berry phase. We have verified the polarization properties of our gratings for laser radiation at 10.6-microm wavelength. 相似文献
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视细胞浓度分布对散射光偏振性的影响 总被引:1,自引:0,他引:1
人眼视网膜是一种具有高散射特性的生物组织。基于米氏散射理论研究光在视网膜组织中的传输过程对生物组织散射成像具有重要意义。根据解剖学上视网膜结构与细胞分布的特点,引入分子动力学领域的静态结构因子修正辐射传递理论,并采用离散坐标法求解视细胞对散射光偏振性的影响。结果表明散射光偏振性取决于视细胞尺寸与浓度分布等因素。在不同的极角和光程位置,散射光束的偏振性呈现波动性变化,视锥细胞核比视杆细胞核具有更强的散射特性,散射光束的偏振特性变化随散射角的增大而增大。 相似文献
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The evolution of an electromagnetic wave with slowly varying polarization, which interacts resonantly with the medium formed by degenerate two-level atoms, is studied using the wave function approach under the conditions of electromagnetically induced transparency. It is shown that the amplitude of the wave field propagates at the velocity of light in such a medium. The equation obtained for the polarization parameter has a solution in the form of a simple wave. The breaking length is determined. It is shown that the velocity of propagation of polarization waves may be much smaller than the velocity of light. The proposed approach is common for two-level systems with an arbitrary degeneracy. The case of a system with Zeeman degeneracy is analyzed in detail. The dependence of the velocity of propagation of the polarization structure on the amplitude and polarization is determined for an arbitrary level degeneracy. The evolution of the polarization structure in such a medium is discussed. 相似文献
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P.P. Sahu 《Applied physics. B, Lasers and optics》2008,92(2):247-252
In this paper, a thermally tunable add/drop multiplexer based on a Y symmetric cascaded Mach–Zehnder (CMZ) coupler is found
to be polarization dependent due to the stress anisotropy caused by local heating to achieve thermooptic phase change. A thermooptic
delay line structure with a stress releasing groove is proposed for reduction of the polarization dependence of a Y symmetric
delay line coupler of high index contrast waveguides. It is seen that thermally tunable transmission characteristics of a
Y symmetric CMZ device based on the proposed structure is almost polarization independent. It is also found that the reduction
of the heating power in the proposed structure is ∼1.6 times smaller than that of the conventional structure.
PACS 29.27.Fh; 52.38.Kd 相似文献
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本文提出了一种“金属栅-开口环/硅环-金属栅”结构的透射式超表面偏振控制器, 研究了入射角度和抽运光对该器件传输及偏振态控制性能的影响. 研究结果表明, 当线偏振太赫兹波垂直入射时, 可对0.39-1.11 THz频段的太赫兹波实现偏振方向90°旋转, 偏振旋转效率为99%, 损耗为1 dB. 对于斜入射的情况, 偏振转换性能在0-60°范围内基本保持不变, 且透过率达到90%以上. 同时, 通过调控抽运光强度的方式, 该器件能够实现对透射与反射太赫兹光束的强度调制, 调制深度均达到90%, 且可以实现太赫兹波偏振分束功能. 该器件可以作为未来太赫兹空间光通信和信息处理的宽带、角度不敏感、可调谐的偏振转换器和分束器. 相似文献