共查询到20条相似文献,搜索用时 46 毫秒
1.
We investigate a periodic slit-groove metal array with converging and diverging shaped channels by using the finite-difference time-domain (FDTD) method. We show that the peaks and dips of the transmission spectra can be tuned by the geometry parameters of the groove. And the resonance modes are strongly correlated with the groove depth and width of both ends of the groove, and the transmission dip between the resonance modes can be modulated by these parameters. However, the distance between the slit and the groove has little influence on the transmission. We show that the periodic slit-groove with diverging and converging shaped channels is useful for the design of plasmonic devices. 相似文献
2.
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
3.
Mark Short Stephen J. Voelkel David A. Kessler 《Proceedings of the Combustion Institute》2021,38(2):2205-2214
We study the effects of non-parallel (diverging or converging) channel walls on flame propagation and acceleration in planar and cylindrical narrow channels, closed at the ignition end and open at the other, accounting for thermal expansion in both the zero Mach number and weakly compressible flow limits. For parallel channel walls, previous work has shown that thermal expansion induces an axial flow in the channel, which can significantly increase the propagation speed and acceleration of the flame. In this study, we consider examples of diverging/converging linear walls, although our asymptotic analysis is also valid for curved walls. The slope of the channel walls is chosen so that the magnitude of the thermal-expansion induced flow through the channel obtained for parallel walls is modified at leading-order, thereby influencing the leading-order flame propagation. For zero Mach number flows, the effect of the diverging/converging channel walls is moderate. However, for weakly compressible flows, the non-parallel walls directly affect the rate at which pressure diffuses through the channel, significantly inhibiting flame acceleration for diverging walls, whereas the flame acceleration process is enhanced for converging walls. We consider several values of the compressibility factor and channel wall slopes. We also show that the effect of a cylindrical channel geometry can act to significantly enhance flame acceleration relative to planar channels. The study reveals several new physical insights on how non-parallel channel walls can influence the ability of flames to accelerate by modifying the flow and pressure distribution induced by thermal expansion. 相似文献
4.
A Compact Optical Switch via Plasmonics of Subwavelength Circular‐Sharp Hole Arrays in Metal Films 下载免费PDF全文
Taiming Sun Zhixiang Deng Jiabing Sheng Zhiyong Chen Weihua Zhu Wei Guo Xinlin Wang 《Annalen der Physik》2018,530(3)
We studied numerically the enhanced optical transmission (EOT) through periodic subwavelength circular‐sharp hole arrays in metallic films with different edge sharp distribution features of unit structures. Detailed studies indicate that the unit structure edge sharp distribution features strongly influence the surface plasmons (SPs). These results demonstrate that the number of edge sharp activated the localized surface plamons (LSP) resonance on the unit structure is changed by rotating the polarization of the incident light, leading to change the infrared transmittance of the array. Moreover, a compact plasmonic switch via periodic circular‐sharp hole arrays based on the dependence of SPs on unit structural edge sharp distributions is proposed. The finding provides a new idea for designing plasmonics devices, and expands the application range of metal micro‐nano structure in the field of optical communications and information processing. 相似文献
5.
《Physics letters. A》2005,344(6):451-456
By using FDTD numerical simulations, we show that mechanism that is different from surface plasmon polaritons set up by the periodicity at the in-plane metal surfaces may account for the superenhanced light transmission through coaxial hole arrays. We propose that resonant cavity-enhanced light transmission is responsible for it. When an axis is introduced into a hole, slits of definite length are formed. We suppose that a coaxial hole will support the standing waves of Fabry–Pérot-like modes with frequency higher than its cutoff frequency if its gap is small enough in comparison to the wavelength of the incident light and if the metal film is thick enough. 相似文献
6.
Experimental studies of extraordinary light transmission through periodic arrays of subwavelength square and rectangular holes in metal films 下载免费PDF全文
We fabricate a series of periodic arrays of subwavelength
square and rectangular air holes on gold films, and measure the
transmission spectra of these metallic nanostructures. By changing
some geometrical and physical parameters, such as array period, air
hole size and shape, and the incident light polarization, we verify
that both global surface plasmon resonance and localized waveguide
mode resonance are influential on enhancing the transmission of
light through nanostructured metal films. These two resonances
induce different behaviours of transmission peak shift. The
transmission through the rectangular air-hole structures exhibits an
obvious polarization effect dependent on the morphology. Numerical
simulations are also made by a plane-wave transfer-matrix method and
in good consistency with the experimental results. 相似文献
7.
《Current Applied Physics》2009,9(4):820-825
We report a simple and cost effective method to fabricate regular metallic particle arrays over large areas with good regularity by using holographic lithography interference for the study of localized surface plasmon. Samples of disk-shaped gold nano-particles arranged in square arrays with lattice spacing ranging from 300 nm to 600 nm were successfully fabricated on glass substrates first by sputtering a thin gold layer onto two-dimensional photoresist templates of hole arrays in square lattice obtained by the holographic method and then removing the photoresist by a lift-off procedure. The plasmonic resonance of the gold nano-particle arrays due to the change of morphology by thermal annealing was studied. The disk-shaped gold nano-particles were found to become more round shaped upon heating and blue shift of the extinction plasmonic band was observed. The results were explained with model calculations using spheroidal particles. 相似文献
8.
The extraordinary light transmission through a 200-nm thick gold
film when passing through different subwavelength hole arrays is
observed experimentally. The sample is fabricated by electron beam
lithography and reactive ion etching system. A comparison between
light transmissions shows that the hole shape changing from
rectangular to diamond strongly affects the transmission intensity
although both structures possess the same lattice constant of
600,nm. Moreover, the position of the transmission maximum
undergoes a spectral red-shift of about 63,nm. Numerical
simulations by using a transfer matrix method reproduce the observed
transmission spectrum quite well. 相似文献
9.
We report the observation of enhanced near-infrared transmission through arrays of subwavelength coaxial metallic structures compared with that through comparable diameter hole arrays as a result of localized electromagnetic modes supported by the complex coaxial unit cell. Polarization and angle-dependent transmission measurements clearly demonstrate the coupling between this localized mode and delocalized surface plasmon modes. A generalized, multiple discrete states Fano line shape provides a good fit to the experimental results. 相似文献
10.
Mikhail I. Charnotskii 《Waves in Random and Complex Media》1994,4(3):243-273
Asymptotic analysis of on-axis intensity fluctuation variance of a finite-sized light beam is performed starting from the functional integral representation for the field in a random medium. Collimated, diverging and converging beams with different diffraction properties are considered. A complete set of asymptotes is obtained using the main and additional coherence channels approach to the fourth moment of field analyses. We study the conditions of weak and strong fluctuation regimes for all these types of beams and obtain relatively simple formulae for on-axis intensity variance, which are valid for the case of stratified turbulence. It is shown that scintillations in the vicinity of the beam focus are governed by double-scattering processes for weak scintillations and double scattering from coherence channels for strong fluctuations. 相似文献
11.
Renlong Zhou Xiaoshuang Chen Shaowei Wang Wei Lu Yong Zeng Hongbo Chen Hongjian Li Hui Xia Lingling Wang 《Solid State Communications》2008,145(1-2):23-28
In this paper we investigated the enhanced transmission and surface plasmon resonance through a thin gold film with a periodic array of subwavelength nanoholes. Both freestanding gold-film nanohole arrays and gold-film nanohole arrays deposited on a gallium arsenide (GaAs) substrate are considered. Periodic arrays of nanoholes exhibit two different surface plasmon resonance features: localized waveguide resonance and the well-recognized photonic crystal resonance. The tangential electric field component is nonzero only in the hole region for a freestanding gold-film nanohole array, but it can exist in the hole region and in the metallic region for a gold-film nanohole array deposited on a GaAs substrate. 相似文献
12.
Shan Huang Jie Li Xuewei Zhang Yimin Kang Ziwei Li Feng Lin Xing Zhu 《Applied Physics A: Materials Science & Processing》2014,115(2):589-593
Abstract We demonstrate that the rectangular nanohole arrays perforated in a 100 nm gold film can be used to tune the polarization direction of the transmitted light with maximum rotation angle of about 30 degrees. Theoretical analysis with the three-dimensional finite-difference time-domain simulations indicates that this phenomenon is attributed to the excitation of the surface plasmon wave on the gold film surface and the resonance of localized surface plasmon in the hole. With multiple plasmon resonances, the plasmonic waveplate can realize multi-wavelength polarization modulation. Our results may be useful to understanding the physical mechanism of enhanced plasmon mediated transmission and potential applications in plasmonic optical components. 相似文献
13.
金属薄膜上制备的表面等离激元颜色滤波器具有很强的颜色可调性. 在200 nm厚的金膜上, 通过聚焦离子束刻蚀, 制备一系列周期逐渐变化的圆形、方形、矩形亚波长尺寸小孔方阵列表面等离激元颜色滤波器, 改变入射光的偏振方向, 观察其超透射滤波现象. 研究发现: 对于矩形小孔阵列, 其透射光颜色随入射光偏振方向的变化而改变; 而对于圆形、方形的小孔阵列, 其透射光颜色对入射光的偏振方向并不敏感. 分析表明, 对于金膜上刻蚀的小孔结构, 虽然结构的周期性导致的表面等离激元极化子会对透射光的颜色变化产生一定影响, 但是随小孔形状变化的局域表面等离激元共振才是影响透射光颜色的决定性因素. 如果入射光没有在小孔中激发出局域表面等离激元, 则表面等离激元极化子对透射光的影响也会消失. 根据不同形状小孔周期结构透射光颜色随入射光的偏振变化特点, 制备出了包含两种小孔形状的复合周期结构. 随着入射光偏振方向的改变, 该结构会显示出不同的颜色图案.
关键词:
表面等离激元极化子
局域表面等离激元
颜色滤波器
亚波长小孔阵列 相似文献
14.
The ultrasonic transmission through plates perforated with 2 × 2 or 3 × 3 square array of subwavelength holes per unit cell are studied by numerical simulations. Calculations are obtained by means of a theoretical model under the rigid-solid assumption. It is demonstrated that when the inter-hole distance within the unit cell is reduced, new transmission dips appear resulting from Wood anomalies that have influence on the second and the third order Fabry-Perot peak. When the inter-hole distance within the unit cell is reduced, the transmission spectrum of the multiple-sublattice holes arrays tends to the transmission spectrum of a plate perforated with only one hole in the unit cell. 相似文献
15.
16.
F.G. Mitri 《Ultrasonics》2010,50(6):620-627
Objective
The present research examines the acoustic radiation force of axisymmetric waves incident upon a cylinder of circular surface immersed in a nonviscous fluid. The attempt here is to unify the various treatments of radiation force on a cylinder with arbitrary radius and provide a formulation suitable for any axisymmetric incident wave.Method and results
Analytical equations are derived for the acoustic scattering field and the axial acoustic radiation force. A general formulation for the radiation force function, which is the radiation force per unit energy density per unit cross-sectional surface, is derived. Specialized forms of the radiation force function are provided for several types of incident waves including plane progressive, plane standing, plane quasi-standing, cylindrical progressive diverging, cylindrical progressive converging and cylindrical standing and quasi-standing diverging waves (with an extension to the case of spherical standing and quasi-standing diverging waves incident upon a sphere).Significance and some potential applications
This study may be helpful essentially due to its inherent value as a canonical problem in physical acoustics. Potential applications include particle manipulation of cylindrical shaped structures in biomedicine, micro-gravity environments, fluid dynamics properties of cylindrical capillary bridges, and the micro-fabrication of new cylindrical crystals to better control light beams. 相似文献17.
We present experimental results of the transmission magnitude and phase change of terahertz pulses through thin metallic films patterned with subwavelength hole arrays on silicon wafers. Terahertz time-domain spectroscopy measurements reveal a sharp phase peak centered on the surface plasmon resonance. Correspondingly, and consistent with the Kramers-Kronig relations, the measured transmission magnitude has the shape of the derivative of this peak. In addition, we determine that the aperture shape has a notable effect on the transmission properties of two-dimensional hole arrays. 相似文献
18.
We investigate the electronic transport properties of gold point contacts with superconducting aluminum leads. The modifications induced by the proximity effect in the quasiparticle density of states at the contact region are measured by tunnel spectroscopy. The theory of transport through multiple Andreev reflections is extended to incorporate these effects and used to determine the number and transmission coefficients of the conduction channels in the contact regime. We find that the smallest contacts, formed by one gold atom between the electrodes, contribute one single channel to the transport with variable transmission T between 0.1 and 1. 相似文献
19.
Superenhanced light transmission through subwavelength rectangular hole
arrays have been reported and some investigations have been made into the
physical origin of this phenomenon [K.J. Klein Koerkamp et al., Phys. Rev. Lett.
92, 183901 (2004)]. In our current work, by performing FDTD (finite
difference in the time domain) numerical simulations, we demonstrate that
mechanism that is different from surface plasmon polaritons set up by the
periodicity at the in-plane metal surfaces may account for this
superenhanced light transmission. We suggest that for arrays of rectangular
holes with small enough width in comparison to the wavelength of the
incident light, standing electromagnetic fields can be set up inside the
cavity by the surface plasmons on the hole walls with its intensity being
substantially enhanced inside the cavity. So resonant cavity-enhanced light
transmission is predominant and responsible for its superenhanced light
transmission. Rectangular holes behave as Fabry-Pérot resonance cavities
except that the frequency of their fundamental modes is restricted by their
TM cutoff frequency. However we believe that both localized surface plasmon
modes and surface plasmon polaritons set up by the periodicity at the
in-plane metal surfaces have their shares in extraordinary optical
transmission of rectangular hole arrays especially when the width of the
rectangular hole is not small enough and the metal film is not thick enough. 相似文献
20.
We find theoretically that an incident laser beam with a diverging (converging) profile on the vacuum–plasma boundary turns out a converging (diverging) beam in the plasma when ε3<0 as if there were a convex (concave) lens at the boundary, ε3 being the dielectric coefficient along the magnetic field. 相似文献