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Scattering of Evanescent Wave by Periodic Array of Nanowires  [PDF]
Leonid L. Frumin,Anton V. Nemykin,Sergey V. Perminov,David A. Shapiro
Physics , 2012,
Abstract: The scattering of electromagnetic wave by a periodic array of nanowires is calculated by the boundary element method. The method is extended to the infinite grating near the interface between two dielectrics. A special Green function is derived that allows to study the evanescent wave. The Rayleigh--- Wood's anomalies are found in the period-to-wavelength dependence of the average Pointing vector in the wave zone. For thin wires the calculations are shown to agree with the two-dimensional coupled dipole approximation.
Evanescent wave diffraction of multi-level atoms  [PDF]
D. Gordon,C. M. Savage
Physics , 1996, DOI: 10.1016/0030-4018(96)00237-4
Abstract: Diffraction of multi-level atoms by an evanescent wave reflective diffraction grating is modeled by numerically solving the time-dependent Schr\"{o}dinger equation. We are able to explain the diffraction observed in experiments with metastable Neon. This is not possible using a two-level atom model. The multi-level model predicts sensitive dependence of diffraction on the laser polarization and on the intensity ratio of incoming and reflected laser beams.
A Numerical Study of Evanescent Fields in Backward-Wave Slabs  [PDF]
M. K. Karkkainen,S. A. Tretyakov,S. I. Maslovski,P. A. Belov
Physics , 2003,
Abstract: Numerical study of evanescent fields in an isotropic backward-wave (BW) (double negative or "left-handed") slab is performed with the FDTD method. This system is expected to be able to restore all spatial Fourier components of the spectrum of a planar source, including evanescent fields, realizing a "superlens". The excitation of surface modes on the interfaces of the slab, which is the key process responsible for the sub-wavelength focusing, is numerically confirmed and the time-domain field behavior is studied. In particular, a numerical verification of the amplification of evanescent modes by an isotropic BW slab with epsilon=mu=-1 is provided.
Phase shifts of atomic de Broglie waves at an evanescent wave mirror  [PDF]
C. Henkel,J. -Y. Courtois,R. Kaiser,C. Westbrook,A. Aspect
Physics , 2003,
Abstract: A detailed theoretical investigation of the reflection of an atomic de Broglie wave at an evanescent wave mirror is presented. The classical and the semiclassical descriptions of the reflection process are reviewed, and a full wave-mechanical approach based on the analytical soution of the corresponding Schr\"odinger equation is presented. The phase shift at reflection is calculated exactly and interpreted in terms of instantaneous reflection of the atom at an effective mirror. Besides the semiclassical regime of reflection describable by the WKB method, a pure quantum regime of reflection is identified in the limit where the incident de Broglie wavelength is large compared to the evanescent wave decay length.
Singular evanescent wave resonances  [PDF]
Yu Guo,Zubin Jacob
Physics , 2013,
Abstract: Resonators fold the path of light by reflections leading to a phase balance and thus constructive addition of propagating waves. However, amplitude decrease of these waves due to incomplete reflection or material absorption leads to a finite quality factor of all resonances. Here we report on our discovery that evanescent waves can lead to a perfect phase and amplitude balance causing an ideal Fabry-Perot resonance condition in spite of material absorption and non-ideal reflectivities. This counterintuitive resonance occurs if and only if the metallic Fabry-Perot plates are in relative motion to each other separated by a critical distance. We show that the energy needed to approach the resonance arises from the conversion of the mechanical energy of motion to electromagnetic energy. The phenomenon is similar to lasing where the losses in the cavity resonance are exactly compensated by optical gain media instead of mechanical motion. Nonlinearities and non-localities in material response will inevitably curtail any singularities however we show the giant enhancement in non-equilibrium phenomena due to such resonances in moving media.
Limits for superfocusing with finite evanescent wave amplification  [PDF]
Reuven Gordon
Physics , 2011, DOI: 10.1364/OL.37.000912
Abstract: Perfect lensing using negative refractive index materials and radiationless electromagnetic interference both provide extreme subwavelength focusing by "amplifying" evanescent wave components that are usually lost. This paper provides a relation between the achievable focus spot size, the amplification available and the focal length. This may be considered as a revised version of Abbe's diffraction limit for focusing systems that have evanescent wave amplification. It is useful in comparing the amplification achieved in various subwavelength focusing implementations, as well as determining when it is better to use existing near-field techniques, such as simple diffraction from an aperture or slit, than to attempt complicated superfocusing.
Characteristics of Metal Enhanced Evanescent-Wave Microcavities  [PDF]
Takashi Wakamatsu
Sensors , 2010, DOI: 10.3390/s100908751
Abstract: This article presents the concept of storing optical energy using a metallic air gap microcavity. Evanescent waves are stored in the air gap of a dielectric/metal/air gap/metal planar microcavity. For an air gap with a micron scale distance between the two metals, incident light excites the optical interface modes on the two metal-air interfaces simultaneously, being accompanied by enhanced evanescent fields. Numerical simulations show that the reflected light depends remarkably upon distributions of the enhanced electric fields in the air-gap at the optical mode excitations. The metallic microcavities have a Q value on the order of 102, as determined from calculations. Experimentally, a small mechanical variation of the air-gap distance exhibited a change of reflectivity.
Artificial magnetic field induced by an evanescent wave  [PDF]
Malgorzata Mochol,Krzysztof Sacha
Physics , 2013, DOI: 10.1038/srep07672
Abstract: Cold atomic gases are perfect laboratories for realization of quantum simulators. In order to simulate solid state systems in the presence of magnetic fields special effort has to be made because atoms are charge neutral. There are different methods for realization of artificial magnetic fields, that is the creation of specific conditions so that the motion of neutral particles mimics the dynamics of charged particles in an effective magnetic field. Here, we consider adiabatic motion of atoms in the presence of an evanescent wave. Theoretical description of the adiabatic motion involves artificial vector and scalar potentials related to the Berry phases. Due to the large gradient of the evanescent field amplitude, the potentials can be strong enough to induce measurable effects in cold atomic gases. We show that the resulting artificial magnetic field is able to induce vortices in a Bose-Einstein condensate trapped close to a surface of a prism where the evanescent wave is created. We also analyze motion of an atomic cloud released from a magneto-optical trap that falls down on the surface of the prism. The artificial magnetic field is able to reflect falling atoms that can be observed experimentally.
Green's function for metamaterial superlens: Evanescent wave in the image  [PDF]
Wei Li,Xunya Jiang
Physics , 2011, DOI: 10.3938/jkps.60.1282
Abstract: We develop a new method to calculate the evanescent wave, the subdivided evanescent waves (SEWs), and the radiative wave, which can be obtained by separating the global field of the image of metamaterial superlens. The method is based on Green's function, and it can be applied in other linear systems. This study could help us to investigate the effect of evanescent wave on metamaterial superlens directly, and give us a new way to design new devices.
Total internal reflection of evanescent plane waves  [PDF]
Akhlesh Lakhtakia,Tom G. Mackay
Physics , 2008, DOI: 10.1088/0143-0807/29/6/N02
Abstract: Describing the phenomenon of total internal reflection in terms of a reflection coefficient of unit magnitude, we found that, not only can propagating plane waves be total internally reflected at the planar interface of two dissimilar, homogeneous, isotropic dielectric-magnetic mediums, but evanescent plane waves can also be. The refracting medium must be the optically denser of the two mediums for total internal reflection of an evanescent plane wave to occur.
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