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亚波长金属光栅在共振波长处有光场局域增强、异常透射等现象,为深入认识其共振机制,本文研究了亚波长金属光栅的表面等离子体激元(SPP)共振特性。通过研究不同金属光栅的几何结构以及金属介电常数对SPP共振波长的影响,获得了3种共振波长的基本物理机制。采用周期边界元法进行数值模拟,在边界积分方程的基础上结合平面波展开方法来处理任意形状的周期性结构。模拟结果表明,3种共振波长可以分别由金属的材料、金属光栅周期和金属光栅厚度所调谐。该研究为微纳米光学器件的设计提供了依据。 相似文献
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表面等离子体可以将光子局域在金属表面附近, 并形成很强的近场能量密度, 可以大大提高金属表面附近分子的发光效率和光电转换吸收材料的利用率, 从而提高发光器件和光电转换器件的效率. 本文研究了在一维周期性金属-介质混合结构的光栅中表面等离子体激元的耦合条件, 给出了耦合效率随着结构和填充因子的变化, 并证明了在光栅的填充因子较高以至光栅的金属间隔较小时, 光子耦合成为表面等离子体的效率较高, 可以达到94%以上.
关键词:
表面等离子体激元
填充因子
光栅
吸收光谱 相似文献
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从平面电介质-金属薄膜-电介质对称结构中表面等离激元的色散方程出发,建立模型推导得到了同轴电介质-金属薄膜-电介质结构中表面等离激元的色散方程,在这种结构中各阶模式都发生了分裂,形成了高折射率高损耗和低折射率低损耗的两种模式,该模型为理解同轴电介质-金属薄膜-电介质结构表面等离激元模式的传播提供了直观的图像。用色散方程计算了0.5~1.5μm波长范围内各阶模式的等效折射率以及传输损耗,并将该结果与有限元方法数值模拟得到的结果进行对比分析,分析表明,两者吻合得很好。并分析了计算结果以及色散方程的适用范围。 相似文献
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表面等离子体激元的若干新应用 总被引:2,自引:0,他引:2
表面等离子体激元(SPPs)是在金属和介质界面传播的一种波动模式。本文首先叙述了SPPs的相关特性和激发方式,给出了一种基于表面等离子体激元共振(SPR)场增强原理产生相干极紫外辐射的方法,利用该方法可极大地提高光源的光子流量。分析了SPPs在生物及医疗领域的新应用,并对其在治疗癌症方面的技术原理进行了讨论。介绍了SPPs在新型光源和能源领域的发展和应用情况,综述了SPPs在太阳能电池、光子芯片以及集成电路方面的新工艺和新技术,包括最近几年来所取得的一些重要成果。最后讨论了SPPs在光存储方面的快速发展和巨大贡献。 相似文献
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近几年,随着光栅和表面等离子体激元的相关理论和研究的进一步深入,基于表面等离激元光栅问题引起广泛关注。随着器件微型化、高集成化的发展,表面等离激元凭借其自身独特性质,对于以光栅为基础的器件的研究发展做出了巨大贡献。本文基于有限元法对表面等离激元光栅进行研究,通过COMSOL软件对介质基板上线光栅入射的平面电磁波进行了有限元仿真建模和分析,计算了横电波TE波和横磁波TM波的折射、镜面反射和一阶衍射的透射和反射系数。研究结果显示所有系数之和始终小于1,TE波入射时镜面反射系数的值随入射角而相对稳定地增大,当TM波入射时这种情况更加明显,大约一半的波被导线吸收,TM波的另一个重要特征是50~60°附近几乎不发生镜面反射。 相似文献
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为了提高顶入射有机薄膜太阳能电池(TOSCs)的光吸收效率,我们将周期性矩形光栅结构引入到TOSCs中,分析了具有光栅结构的空气/Ag_1/有源层/Ag_2/空气(IMIMI)结构理想模型中复合表面等离子激元(SPPs)与微腔模式的耦合机制。通过调节光栅周期和有源层厚度,实现了复合SPPs、微腔模式以及有机材料本征吸收3个区域的重合。由于复合SPPs与微腔模式的反交叉耦合作用形成了表面等离子体-微腔激元,其局域场增强作用有效地提高了有源层的光吸收效率,提高了近19%。 相似文献
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为提高太赫兹近场显微成像技术的分辨率,设计了一款在Teflon探针的尖锥形表面镀上厚度渐变、具有相同占空比的超薄金属银制条带的探针,用于实现探针尖端处人工表面等离激元的激发和太赫兹波的亚波长聚焦.研究表明,对于频率为0.1 THz的入射波,厚度渐变镀银条带探针产生的紧聚焦光场的尺寸可稳定在20μm左右(λ/150),探针尖端处最大电场强度为入射电场强度的849倍.研究还发现,周期性金属条带的数目和入射电场的偏振方向可对探针尖端处产生的紧聚焦光斑的尺寸和电场强度等进行灵活有效的调控. 相似文献
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The reflection of X-band microwaves (8-12 GHz) from a metallic aluminum (Al) surface with groove grating corrugations was investigated experimentally. It was shown that the reflection of p-polarization is much less than the microwave reflected from the corresponding area of an unruled Al surface, with selective wavelength. The experimental results demonstrated that the anomalous microwave reflection is strongly associated with the excitation of spoof surface plasmons at the Al-air interface by the surface grating coupler. This near-total absence of reflected microwaves is similar to the famous Wood's anomaly in the optical regime and is of fundamental importance to the applications of spoof surface plasmons in the microwave regime. 相似文献
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A slow-wave structure (SWS) with two opposite gratings inside a rectangular
waveguide is presented and analysed. As an all-metal slow-wave circuit, this
structure is especially suited for use in millimetre-wave travelling wave tubes
(TWTs) due to its advantages of large size, high manufacturing precision and good
heat dissipation. The first part of this paper concerns the wave properties of this
structure in vacuum. The influence of the geometrical dimensions on dispersion
characteristics and coupling impedance is investigated. The theoretical results show
that this structure has a very strong dispersion and the coupling impedance for the
fundamental wave is several tens of ohms, but the coupling impedance for --1 space
harmonic wave is much lower than that for the fundamental wave, so the risk of
backward wave oscillation is reduced. Besides these, the CST microwave studio is
also used to simulate the dispersion property of the SWS. The simulation results
from CST and the theoretical results agree well with each other, which supports the
theory. In the second part, a small-signal analysis of a double rectangular
waveguide grating TWT is presented. The typical small-signal gain per period is
about 0.45 dB, and the 3-dB small-signal gain bandwidth is only 4\%. 相似文献
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将任意形状槽的连续轮廓近似用一系列相连的矩形阶梯近似,利用各阶梯面上导纳的匹配,以及槽与互作用区边界场的连续与匹配条件,获得了具有任意槽的矩形波导栅慢波结构的色散方程和耦合阻抗的表达式,并进行理论上的验证.加工制作了矩形槽波导栅模型,冷测表明理论值与测量值相吻合.分别求解几种特殊槽形矩形波导栅慢波结构的色散特性及耦合阻抗,其中,三角形结构的色散和耦合阻抗均最弱,而倒梯形结构色散最强,耦合阻抗最大.
关键词:
矩形波导栅
任意槽
色散特性
慢波结构 相似文献
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We investigated the characteristics of transmitted light from propagating surface plasmons based on rectangular silver gratings. The results calculated by rigorous coupled-wave analysis presented that silver diffraction gratings can produce significant transmittance and conversion efficiency, comparable to the case of dielectric gratings. Especially, silver gratings optimized at a wide range of grating thickness and period may lead to an improved diffraction efficiency larger than 64%. Moreover, the effect of silver oxide layer on the transmittance was examined and a bimetallic structure with a thin gold coating was introduced to prevent an oxidation of silver substrates. As a practical sensor application, silver grating-based surface plasmon resonance (SPR) configuration showed an enhanced sensitivity associated with an increase of surface reaction area and strong excitations of local plasmon fields, outperforming a conventional thin-film-based SPR structure. 相似文献
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O. R. Matov O. V. Polischuk V. V. Popov 《International Journal of Infrared and Millimeter Waves》1993,14(7):1455-1470
The spectrum of electromagnetic (EM) radiation from two-dimensional(2D) plasmons in a semiconductor-dielectric structure with metal grating has been calculated in a strict electromagnetic approach. It is shown that radiation frequency and linewidth vary over a broad range of magnitude as a function of the grating parameters. The radiative decay linewidth is found to be two orders of magnitude larger than expected from the perturbation theory. Comparison of the results with previously published experimental data on 2D plasmons in GaAs heterostructures makes us conclude that the main contribution to the experimental decay linewidth arises from dielectric losses in the layers of the structure. 相似文献
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本文提出了一种基于人工表面等离激元的频率选择结构的设计方法:将设计的频率选择表面和金属鱼骨结构阵列相结合得到一种新的频率选择结构.文中采用这种方法设计了一种具有陡截止和高透、高抑制性能的双通带频率选择结构.该结构由金属鱼骨结构阵列和上下两层相同的频率选择表面复合而成.通过仿真可得,该结构的两个通带频率范围分别是3.0–4.1和10.5–10.9 GHz,透射率均在-0.5 dB以上.透射率低于-10 dB的频率范围是4.7–9.2和12.1–18 GHz.在12.4–15.5 GHz频率范围内,该结构的透射率甚至低于-20 dB.在通带内,电磁波可以高效地透过该结构;在阻带内,该结构对电磁波的透射具有较好的抑制作用.测试结果表明用这种方法设计出的频率选择结构的实际性能和仿真基本一致.在金属鱼骨结构空隙中填入轻质泡沫后该结构具有一定的力学承载性能,可以实现结构功能一体化的设计. 相似文献