共查询到20条相似文献,搜索用时 281 毫秒
1.
Elena Eremina Yuri Eremin Natalia Grishina Thomas Wriedt 《Optics Communications》2008,281(13):3581-3586
The discrete sources method has been extended to analyze the scattering behavior of a cylindrical nanohole in a noble-metal film deposited on a glass prism. The dependence of the transmitted intensity on the incident angle has been investigated. Extreme transmission of the incident plane wave has been detected in the evanescent waves area. 相似文献
2.
Martin Šiler 《Optics Communications》2007,275(2):409-420
We describe a general way how to calculate analytically optical forces acting on Rayleigh particles or colloids placed into interference field made by evanescent waves. In this paper we focus on a configuration with three interfering waves and we present a comprehensive analysis of optical trap positions, depths, and forces depending on the configuration and polarisation of the incident waves. Particle behaviour is predicted including optical sorting according to the particle refractive index. 相似文献
3.
研究基于蜷曲空间结构的近零折射率声聚焦透镜.根据近零折射率材料的声波方向选择机理,采用蜷曲空间结构为基本单元进行排列,设计具有特定入射与出射界面的几何结构,对透射声波的出射方向进行调控,实现了平面声波与柱面声波的聚焦效应,并深入讨论了透镜内部刚性散射体对声聚焦性能的影响.在此基础上,改变近零折射率透镜的出射界面,可以精确调控声波阵面的形状与方向.该类型透镜具有单一的单元结构、高聚焦性能及高鲁棒性等优点.研究结果为设计新型近零折射率声聚焦透镜提供了理论指导与实验参考,同时也为研究声波阵面的调控提供了新思路. 相似文献
4.
Elena Eremina Yuri Eremin Natalia Grishina Thomas Wriedt 《Journal of Quantitative Spectroscopy & Radiative Transfer》2009,110(14-16):1518-1525
The effect of enhanced optical transmission through subwavelength holes and their arrays is used for multiple practical applications especially in optical antennas and local biosensors design. This effect is usually considered under excitation of plane wave propagating at the normal direction to the screen surface. In this work the effect of extreme transmission through the hole in the evanescent wave's area is in focus. The discrete sources method has been applied to analyse the spectral characteristics of light scattered by a cylindrical nanohole in a noble-metal film on a prism surface. The influence of the wavelength, incident angle, film materials and hole's filling on the scattering characteristics has been investigated. A close correlation between the effect of extreme transmission and the surface plasmon resonances has been detected. 相似文献
5.
O. Costa De Beauregard 《International Journal of Theoretical Physics》1973,7(2):129-143
Four generalisations of results appearing in a previous paper, referred to as I, are here produced. (1) Formulas for the field strengths of the evanescent wave generated inside a vacuum sandwiched between two identical refracting media propagating symmetrical incident plane waves; the classical exponential damping factor being then replaced by hyperbolic cosines or sines (according to the field components), an extremely close approximation to a plane tachyon wave is thus obtained; (2) Compact formulas for the case where the evanescent wave is generated by a superposition of plane incident waves with propagation vectors k parallel to a common incidence plane; (3) Compact formulas for the other typical case where the dispersion on k is parallel to the reflecting plane; (4) Formulas for refraction and total reflection of a photon with a non-zero rest mass.We take the opportunity of this paper to review briefly various articles that had escaped us, where a transverse energy flux inside Fresnel's evanescent wave was discussed, and also some recent papers dealing with quantisation of the evanescent wave or related topics. 相似文献
6.
A. V. Razin 《Radiophysics and Quantum Electronics》2010,53(7):417-431
We use the Born approximation of the perturbation method to solve the problem of scattering of a harmonic Rayleigh surface
acoustic wave by a weak-contrast inhomogeneity that is small compared with the wavelength and is located in a solid half-space
near its boundary. The material of the inhomogeneity differs from the material of the half-space only in its density. The
Rayleigh wave incident on the inhomogeneity is excited by a monochromatic surface force source acting normally to the half-space
boundary. We derive expressions for the displacement fields in the scattered spherical compressional and shear (SV- and SH-polarized)
waves. Scattering of the Rayleigh wave into a Rayleigh wave is studied in detail. We find expressions for the vertical and
horizontal components of the displacement vector in the scattered Rayleigh wave as well as its radiated power. It is shown
that the field of the scattered surface wave is mainly formed by vertical oscillations of the inhomogeneity in the field of
the incident wave. In this case, the radiated power for the scattered Rayleigh wave formed by vertical motion of the inhomogeneity
in the incident-wave field depends on the depth of the inhomogeneity as the fourth power of the function describing the well-known
depth dependence of the vertical displacements in the Rayleigh surface wave. Correspondingly, the dependence of the radiated
power for the scattered Rayleigh wave formed by horizontal motion of the inhomogeneity depends on its location depth as the
fourth power of the depth dependence of the horizontal displacements in the Rayleigh surface wave. We perform calculations
of the ratio between the powers of the scattered and incident Rayleigh waves for different ratios between the velocities of
the compressional and shear waves in a solid. It is shown that the radiated power for the scattered surface wave decreases
sharply with increasing depth of the subsurface-inhomogeneity location. Thus, the scattering of a Rayleigh wave into a Rayleigh
wave is fairly efficient only when the location depth of the inhomogeneity does not exceed about one-third of the wavelength
of the shear wave in an elastic medium. 相似文献
7.
8.
We propose and develop a new solid immersion lens (SIL), which is called the multilevel phase Fresnel zone plate lens (FZPL) for the near-field (evanescent wave) microscopy. The simple analysis is presented by using the scalar diffraction theory. The outstanding advantages of this FZPL are that it both focuses incident waves and produces evanescent waves. A FZPL can effectively concentrate the high angle rays important for the high resolution in comparison with the conventional SILs. The optical system equipped with the FZPL is not only simple in the assembly but also effective in making an optical head unit. 相似文献
9.
采用将有限声束分解为一系列平面波的方法,对液固界面声束的声反射问题进行了数值研究,结果表明,当声束入射角为瑞利疲激角时,反射声速有明显位移;当声束在液固界面“掠射”时,反射声速显著变宽,文中还讨论了束宽对反射声速横截面上声场分布的影响。 相似文献
10.
Two counter-propagating evanescent beams are used to align and manipulate polystyrene particles on a prism surface. Since the radiation pressure transferred laterally from the evanescent wave is negated on both sides, particles can be stably aligned. By projecting a circular and a linear beam spot onto the interface, both multiple and single arrays of particles are achieved. Arrays of particles trapped on the interface can be easily moved adjusting the intensity of incident beams on either side. We also simulate electromagnetic distribution of scattering light that is converted from the evanescent wave using the FDTD method. The results show that scattering light converts from an evanescent wave propagating through a particle array and has a distance longer than that propagating from a normal evanescent wave. 相似文献
11.
The present investigation concerns the propagation of surface waves at the vacuum-solid interface of a solid which is isotropic and thermoviscoelastic, i.e., for which the effects of heat conductivity need to be taken into account. Calculations show that, in addition to the Rayleigh wave, a thermal surface wave propagates that couples both the thermal and the elasticity effects. This latter wave is interpreted in terms of evanescent plane waves. The displacement field associated with this wave is calculated and interpreted. Some experimental results are also presented. 相似文献
12.
We describe a way to generate subdiffraction light spots that can be moved over a surface without resorting to near-field manipulation, nonlinear effects, or negative index materials. We use a periodically patterned substrate that converted efficiently, through scattering, the impinging propagative waves into evanescent ones. Then we optimize the wave front of the incident propagative beam so that the grating-scattered evanescent waves interfere constructively at the focal point. Numerical simulations show that focus spots as small as one-sixth of a wavelength can be obtained at any point on the substrate. One foreseen application is high resolution surface imaging. 相似文献
13.
We present the results of studying the vibrational velocity distribution over the surface of cylindrical ultrasound transducers
by acoustic holography. We describe two approaches for acoustic holography: the spatial spectrum method and the Rayleigh integral
method. In the case of cylindrical sources the spectral method has a specific feature in comparison to the case of quasi-plane
sources: small-scale spectrum components having the form of evanescent (nonpropagating) waves near the source, turn into propagating
waves at a certain distance from the source. The use of such a mixed type of waves makes it possible to increase the holographic
resolution. To conduct holography of cylindrical sources by the Rayleigh integral method, a modification consisting in the
superimposing of boundaries on the integration region is proposed. We present the results of numerical simulation and physical
experiments on holography of small cylindrical piezoelectric transducers. We demonstrate that the proposed methods of holography
make it possible to recover the vibration structure of source surfaces up to order of the wavelength scales. 相似文献
14.
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15.
The method of wave function expansion is adopted to study the scattering of a plane harmonic acoustic wave incident at an arbitrary angle upon an arbitrarily thick cylindrically orthotropic homogeneous cylindrical shell submerged in and filled with compressible ideal fluids. A laminate approximate model and the so-called state space formulation in conjunction with the classical transfer matrix (T-matrix) approach are employed to present an analytical solution based on the three-dimensional exact equations of anisotropic elasticity. The solution is used to correlate the perturbation in the material elastic constants of an air-filled and water-submerged aluminium cylindrical shell to the sensitivity of resonances associated with various modes of wave propagation appearing in the backscattered amplitude spectrum (i.e., axially guided, Lamb, Rayleigh and Whispering Gallery waves). The effects of shell wall thickness as well as inner fluid loading on the frequency response of the shell are also examined. A limiting case is considered and good agreement with the solution available in the literature is obtained. 相似文献
16.
17.
Yu. M. Zaslavskii 《Acoustical Physics》2004,50(1):46-51
Scattering of high-frequency transverse and longitudinal plane waves incident on a spherical cavity located at a small depth under the surface of a half-space is considered. The cavity oscillates as a whole in the field of a low-frequency Rayleigh surface wave, the oscillation vectors of the longitudinal, transverse, and surface waves being coplanar. The cavity radius is assumed to be small compared to the wavelengths of the sounding wave and the pumping surface wave. The scattered compression and shear waves at the combination frequencies ω±Ω are calculated in the dipole approximation. Expressions obtained describe the qualitative behavior of the combination-frequency signal levels produced at the outputs of horizontally and vertically oriented geophones moving over the free surface of the elastic half-space. 相似文献
18.
Fang Xue-Qian Zhang Le-Le Liu Jin-Xi 《Applied Physics A: Materials Science & Processing》2012,106(3):625-633
Taking into account the size of the nanostructure, the effect of surface/interface stiffness on the dynamic stress around
a cylindrical nano-inhomogeneity embedded in an elastic half-plane subjected to anti-plane shear waves is investigated. The
boundary condition at the straight edge of the half-plane is traction free, which is satisfied by the image method. The analytical
solutions of displacement fields are expressed by employing a wave function expansion method. The addition theorem for a cylindrical
wave function is applied to accomplish the superposition of wave fields in the two half-planes. Analyses show that the effect
of the interface properties on the dynamic stress is significantly related to the nano-scale distance between the straight
edge and the center of the cylindrical nano-inhomogeneity. The frequency and incident angle of incident waves and the shear
modulus ratio of the nano-inhomogeneity to matrix also show different effect on the dynamic stress distribution when the inhomogeneity
shrinks to nano-scale. Comparison with the existing results is also given. 相似文献
19.
We propose a novel scheme to form a 2D dark optical surface lattice (DOSL) for cold atoms on the surface of the dense flint glass by using two sets of blue-detuned evanescent wave interference fields and a blue-detuned evanescent wave field. In the 2D DOSL, cold atoms will be trapped in the vicinity of minimum intensity and suffered the minimal light shift as well as the lowest coherence loss. The total potential and trap-depth of the individual optical micro-trap in the 2D DOSL are high enough to trap cold atoms (T = 120 μK) released from the standard magneto-optical trap (MOT), and atoms trapped in the 2D DOSL can be cooled to several μK with the efficient intensity-gradient Sisyphus cooling. The lattice constant of the DOSL can be controllable by changing the incident angles of lights. 相似文献
20.
T. I. Kuznetsova N. A. Raspopov 《Journal of Experimental and Theoretical Physics》2014,118(3):395-400
A one-dimensional photonic crystal and an incident light wave that is noncollinear with the permittivity gradient of the crystal are considered. On the basis of coupled-mode equations, eigensolutions for the fields are obtained; a special focus is placed on evanescent waves. Field transformation at the crystal-air and crystal-metal interfaces is analyzed. A condition for the resonance excitation of surface waves at the interface between a crystal and a metal is obtained, and an estimate is given for the efficiency of transformation of the original traveling wave into a surface wave. 相似文献