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1.
Transmission behavior of light through a grating consisting of n-doped semiconductor with subwavelength slits under the application of external static magnetic fields is investigated. As dielectric constant of n-doped semiconductor can be substantially altered by applied magnetic field, in the Voigt configuration and for TM-polarized illumination, two transmission resonance peaks associated with localized waveguide modes of slits are significantly shifted toward the lower frequency regime with the increase of the applied magnetic field. These characteristics can be assigned to a reduction of effective plasma frequency of n-doped semiconductor under the applied magnetic field. Our findings may provide possibility for achieving tunable transmission resonance spectrum. 相似文献
2.
Transmission through array of subwavelength metallic slits curved with a single step or mutli-step 下载免费PDF全文
The transmission of normally incident plane wave through an array of subwavelength metallic slits curved with a sin- gle step or mutli-step has been explored theoretically. The transmission spectrum is simulated by using the finite-difference time-domain method. The influences of surface plasmon polaritons make the end of finite long sub-wavelength metallic slit behaves as magnetic-reflecting barrier. The electromagnetic fields in the subwavelength metallic slits are the superpo- sition of standing wave and traveling wave. The standing electromagnetic oscillation behaves like LC oscillating circuit to decide the resonance wavelength. Therefore, the parameters of adding step may change the LC circuit and influence the transmission wavelength. A new explanation model is proposed in which the resonant wavelength is decided by four factors: the changed length for electric field, the changed length for magnetic field, the effective coefficient of capacitance, and the effective coefficient of inductance. The effect of adding step is presented to analyze the interaction of two steps in slit with mutli-step. This explanation model has been proved by the transmission through arrayed subwavelength metallic slits curved with two steps and fractal steps. All calculated results are well explained by our proposed model. 相似文献
3.
金属单缝纳米结构因为结构简单、易于集成,常用在基于表面等离极化激元(surface plasmon polaritons,SPPs)的纳米结构中构建光源.但是,金属亚波长单缝结构一直存在透射率低的问题,如何提高其透射率一直是研究的重点.为了更好地提高金属亚波长单缝的透射率,本文对之前文献提出的分布式布拉格反射镜(distributed bragg reflector,DBR)和金属银薄膜纳米缝结构进行改进,在金属银薄膜两侧设计凹槽.当TM偏振光由DBR侧入射至DBR-银纳米缝结构时,DBR-银膜界面上和银膜入射侧凹槽一起激发的塔姆激元(Tamm plasmon polaritons,TPPs)和SPPs,以及纳米缝和银膜出射侧凹槽对的SPPs同时激发,利用凹槽激发的SPPs和银膜表面处的TPPs-SPPs混合模式的干涉相长耦合作用,通过塔姆激元的局域场增强效应和两侧凹槽与单纳米缝的干涉相长耦合作用进一步提高了表面等离极化激元模式的激发效率,再加上纳米缝中的类法布里-珀罗腔共振效应,使纳米缝的透射率得到增强.本文采用有限元方法研究了DBR-银纳米缝结构上单纳米缝加凹槽的透射特性.经过一系列参数优化,使DBR-银纳米缝凹槽结构的最大透射率增加到0.22,相对于TiO_2-银纳米缝结构的透射率(0.01)提高了22倍,比文献[23]得到的最大透射率0.166有所提高.研究结果在纳米光源设计、光子集成电路和光学信号传输等相关领域具有一定的应用价值. 相似文献
4.
In this paper, we have proposed a plasmonic splitter which is composed of a subwavelength slit and two different metal-insulator-metal (MIM) waveguides with periodic grooves. The slit is used to excite surface plasmon polaritons (SPPs) at certain wavelengths. By setting the SPPs resonance wavelengths of the slit as the Bragg wavelengths of MIM waveguides, the SPPs of different wavelengths are able to be confined and guided in the two different MIM waveguides. The numerical results of two-dimensional finite difference time domain (2D-FDTD) demonstrate that our proposed structure is capable of splitting light into two MIM waveguides. 相似文献
5.
全光二极管是集成光子回路上最基本的光子器件,如何有效增强全光二极管的单向透射性,提高消光比一直是学者们研究的重点.当前,利用表面等离极化激元(surface plasmon polaritons,SPPs)和复合衍射衰逝波(composite diffracted evanescent wave,CDEW)的亚波长金属微纳结构构建全光二极管器件还鲜有研究.因此,开发出一种可调制的全光二极管,对未来制备复杂的光子回路具有重要意义.本文提出了一种基于SPPs-CDEW混合模式设计全光二极管的方法和结构,该结构结合纳米缝中的类法布里-珀罗共振效应,利用结构参数对SPPs进行调控,实现了光束单向透过的功能.首先,利用理论推导和有限元算法分析了单缝-对称双凹槽纳米结构的透射增强现象,提出了透射增强和削弱的物理机理.其次,计算出规约化透射率随单狭缝和凹槽对之间距离变化的远场透射谱,给出的理论和数值计算结果符合得很好.最后,通过此透射谱精确确定凹槽的位置和数量,得出上表面对称分布五对增强透射凹槽、下表面六对抑制透射凹槽的最优全光二极管结构,有效增强了全光二极管的单向透射性,提高了消光比,最大消光比可以达到38.3 dB,即正向透射率是反向透射率的6761倍,比已有文献提高了14.6 dB,并在850 nm左右有70 nm宽的工作波长带宽(20 dB).本文提出的光二极管结构简单,宽带宽工作,易于集成,耦合效率高,研究结果对光学信号传输、集成光回路、超分辨率光刻等相关领域具有潜在的应用价值. 相似文献
6.
Y. Pang 《Optics Communications》2007,280(1):10-15
Transmission of polarized light through subwavelength slit apertures is studied in visible and near infrared range wavelengths. We examine the roles played by the slit apertures, such as length, depth, period and number of slits. The experiment results, including dispersion curves, demonstrate among other things that the surface plasmon polariton and Fabry-Perot waveguide modes collectively dictate the transmission properties of subwavelength slit arrays and that as they approach each other, not only large gaps are formed but also mode interconversion occurs. These findings are discussed and compared to theoretical predictions. 相似文献
7.
We numerically investigated the tunability of resonance terahertz frequencies of enhanced transmission through a two-dimensional array of holes perforated on a semiconductor film by external static magnetic fields using FDTD methods. We found that the in-plane surface-plasmon polaritons-induced transmission peaks shifted appreciably to longer wavelengths when a moderate magnetic field is applied parallel to the patterned semiconductor film and perpendicular to the electric fields of the incident electromagnetic waves. In particular, there is another transmission peak on which the tuning effect is neglectable, indicating that different mechanism accounts for it. 相似文献
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9.
We present a design for tunable directional beaming through a subwavelength metallic double slit surrounded by dielectric surface-relief gratings.On-axis and off-axis beaming can be switched by controlling the incident angle to asymmetrically excite surface plasmon polaritons(SPPs) that are subsequently coupled out to propagating beams by the two gratings on the left and the right sides of the double slit.Furthermore,the division of optical power into two off-axis beaming directions can be tuned smoothly by varying the incident angle while keeping the total power almost unchanged.The mechanism of this effect is analyzed theoretically and verified using rigorous numerical simulations. 相似文献
10.
S.V. Kukhlevsky M. Mechler O. Samek K. Janssens 《Applied physics. B, Lasers and optics》2006,84(1-2):19-24
We present an analytical model of the resonantly enhanced transmission of light through a subwavelength nm-size slit in a
thick metal film. The simple formulae for the transmitted electromagnetic fields and the transmission coefficient are derived
by using the narrow-slit approximation and the Green’s function formalism for the solution of Maxwell’s equations. The resonance
wavelengths are in agreement with the semi-analytical model [Y. Takakura, Phys. Rev. Lett. 86, 5601 (2001)], which solves
the wave equations by using the Rayleigh field expansion. Our formulae, however, show great resonant enhancement of a transmitted
wave, while the Rayleigh expansion model predicts attenuation. The difference is attributed to the near-field subwavelength
diffraction, which is not considered by the Rayleigh-like expansion models.
PACS 42.25.Bs; 42.65.Fx; 42.79.Ag; 42.79.Dj 相似文献
11.
F. Zhai Y. Guo B.-L. Gu 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(3):405-411
By use of the scattering matrix method, we investigate the coupling effects of layers on spin-polarized transport through
semimagnetic semiconductor heterostructures with triple paramagnetic layers. Due to the coupling between double non-magnetic
layers or among triple paramagnetic layers, spin tunneling exhibits interesting and complex features, which are determined
by the structural configuration, the external fields as well as the spin orientations. It is shown that for electrons with
either spin orientation tunneling through the symmetric or asymmetric heterostructures with triple paramagnetic layers, transmission
resonances can approach the optimum under several biases. Moreover, for asymmetric structures, the resonant enhancement can
occur under both several positive and negative biases. The spin-dependent resonant enhancement is also clearly reflected in
the current density. In addition, for spin electrons traversing the multilayer heterostructure, the resonant splitting occurs
in the transmission, which shows rich variations with the bias. These interesting results may be helpful to the development
of spintronic devices.
Received 28 April 2001 相似文献
12.
Controlling the phase delay of light transmitted through double-layer metallic subwavelength slit arrays 总被引:1,自引:0,他引:1
Marcet Z Paster JW Carr DW Bower JE Cirelli RA Klemens F Mansfield WM Miner JF Pai CS Chan HB 《Optics letters》2008,33(13):1410-1412
We demonstrate that the phase of light transmitted through double-layer subwavelength metallic slit arrays can be controlled through lateral shift of the two layers. Our samples consist of two aluminum layers, each of which contains an array of subwavelength slits. The two layers are placed in sufficient proximity to allow coupling of the evanescent fields at resonance. By changing the lateral shift between the layers from zero to half the period, the phase of the transmitted electromagnetic field is increased by pi, while the transmitted intensity remains high. Such a controllable phase delay could open new capabilities for nanophotonic devices that cannot be achieved with single-layer structures. 相似文献
13.
Analysis of phase shift of surface plasmon polaritons at metallic subwavelength hole arrays 下载免费PDF全文
We present the transmission spectra of light transmitting a metallic thin film perforated with differently shaped sub- wavelength hole arrays, which are calculated by a plane-wave-based transfer matrix method. We analyze the transmission peak positions and the phase-shift angles of different surface plasmon polariton (SPP) modes by using the microscopic theoretical model proposed by Haitao Liu and Philippe Lalanne [Liu Haitao, and Lalanne Philippe 2008 Nature 452 728], in which the phase shift properties of the SPPs scattered by the subwavelength hole arrays are considered. The results show that the transmission peak position and the minus phase shift angle of the SPP increase as the hole size increases. On the other hand, the effective dielectric constant of the metallic film can be deduced by the microscopic theoretical model. 相似文献
14.
《中国光学快报(英文版)》2021,(4)
In this work, inspired by advances in twisted two-dimensional materials, we design and study a new type of optical bi-layer metasurface system, which is based on subwavelength metal slit arrays with phase-gradient modulation, referred to as metagratings(MGs). It is shown that due to the found reversed diffraction law, the interlayer interaction that can be simply adjusted by the gap size can produce a transition from optical beam splitting to high-efficiency asymmetric transmission of incident light from two opposite directions. Our results provide new physics and some advantages for designing subwavelength optical devices to realize efficient wavefront manipulation and one-way propagation. 相似文献
15.
Optical control over surface-plasmon-polariton-assisted THz transmission through a slit aperture 总被引:1,自引:0,他引:1
Hendry E Garcia-Vidal FJ Martin-Moreno L Rivas JG Bonn M Hibbins AP Lockyear MJ 《Physical review letters》2008,100(12):123901
We demonstrate optical control over the transmission of terahertz (THz) radiation through a single subwavelength slit in an otherwise opaque silicon wafer. The addition of periodic corrugation on each side of the wafer allows coupling to surface plasmon polaritons, so that light not impinging directly on the slit can contribute to the transmission. A significant enhancement of the THz transmission can be achieved through control of the surface wave propagation length by excitation at optical wavelengths. The observed transmission increase is in distinct contrast to the reduction reported for photoexcitation of arrays of holes in semiconductors. 相似文献
16.
17.
We investigate the relationship between the transmission and the layer distance of double-layer gold slit arrays by using the finite-difference time-domain method.The results show that the transmission properties can be influenced strongly by layer distance.We attribute the two types of resonant modes to surface plasmon resonance and the localised waveguide resonance.We find that the localised waveguide transmission peak redshifts and becomes broader with increasing layer distance D.We also describe and explain the splitting,shift,and degeneration of the surface plasmon resonant transmission peak theoretically.In addition,to clarify the physical mechanism of the transmission behaviours,we analyse the distributions of electric field and total energy for the three transmission peaks with distance D=45 nm for the double-layer system.Light transporting behaviours are mostly concentrated in the region of the slits as well as the interspaces of the two layers,and for different resonant wavelengths the electric field and energy distributions are different.It is expected that the results obtained here will be helpful for designing subwavelength metallic grating devices. 相似文献
18.
Martín-Moreno L García-Vidal FJ Lezec HJ Pellerin KM Thio T Pendry JB Ebbesen TW 《Physical review letters》2001,86(6):1114-1117
We present a fully three-dimensional theoretical study of the extraordinary transmission of light through subwavelength hole arrays in optically thick metal films. Good agreement is obtained with experimental data. An analytical minimal model is also developed, which conclusively shows that the enhancement of transmission is due to tunneling through surface plasmons formed on each metal-dielectric interface. Different regimes of tunneling (resonant through a "surface plasmon molecule," or sequential through two isolated surface plasmons) are found depending on the geometrical parameters defining the system. 相似文献
19.
20.
Meng-Dong He Zhi-Qiang Gong Shui Li Yong-Feng Luo Jian-Qiang Liu Xiaoshuang Chen 《Solid State Communications》2010,150(29-30):1283-1286
The transmission characteristics of a metallic slit with a bar are investigated by using the two-dimensional finite difference time-domain method. It is found that the introduction of a bar enriches the transmission spectrum. As the bar locates at the center of the electric (magnetic) field antinodes, the transmission peaks have longer (shorter) wavelengths in comparison with the corresponding resonant peaks of the single slit. It is true for both the fundamental mode and second order mode. The proposed mode in a previous paper [Y. Wang, Y. Wang, Y. Zhang, S. Liu, Opt. Express 17 (2009) 5014] can well explain the above phenomenon. The increase in ability to accumulate charge or decrease in the length of current flow dominates when the bar lies at different positions, which results in a redshift or blueshift of transmission peaks. Moreover, it is also found that the transmission spectrum of the studied structure can be tuned by adjusting the length and width of the bar. It is expected that our results may be utilized to control the electromagnetic wave in subwavelength optics. 相似文献