Squeezing electromagnetic energy with a dielectric split ring inside a permeability-near-zero metamaterial

A novel electromagnetic energy squeezing mechanism is proposed based on the special properties of permeability-near-zero metamaterials. Nearly no energy stream can enter a conventional dielectric region positioned inside a permeability-near-zero material. When a source is surrounded by a dielectric split ring (encloser with a gap opened), the electromagnetic energy generated by the source is forced to propagate through the gap. When the gap is narrow, the energy stream density becomes very large and makes the magnetic field enhanced drastically in the gap. The narrow gap can be long and bended. This provides us a method to obtain strong magnetic field without using resonance enhancement.Comment: 17pages, 4 figure

Bessel beam propagation: Energy localization and velocity

The propagation of a Bessel beam (or Bessel-X wave) is analyzed on the basis of a vectorial treatment. The electric and magnetic fields are obtained by considering a realistic situation able to generate that kind of scalar field. Specifically, we analyze the field due to a ring-shaped aperture over a metallic screen on which a linearly polarized plane wave impinges. On this basis, and in the far field approximation, we can obtain information about the propagation of energy flux and the velocity of the energy.Comment: 6 pages, 4 figure

Efficient channeling of fluorescence photons from single quantum dots into guided modes of optical nanofiber

We experimentally demonstrate the efficient channeling of fluorescence photons from single q-dots on optical nanofiber into the guided modes, by measuring the photon-count rates through the guided and radiation modes simultaneously. We obtain the maximum channeling efficiency to be 22.0 (\pm4.8)% at fiber diameter of 350 nm for the emission wavelength of 780 nm. The results may open new possibilities in quantum information technologies for generating single photons into single-mode optical-fibers.Comment: 5 pages, 4 figure

Abnormal enhancement of electric field inside a thin permittivity-near-zero object in free space

It is found that the electric field can be enhanced strongly inside a permittivity-near-zero object in free space, when the transverse cross section of the object is small and the length along the propagation direction of the incident wave is large enough as compared with the wavelength. The physical mechanism is explained in details. The incident electromagnetic energy can only flow almost normally through the outer surface into or out of the permittivity-near-zero object, which leads to large energy stream density and then strong electric field inside the object. Meanwhile, the magnetic field inside the permittivity-near-zero object may be smaller than that of the incident wave, which is also helpful for enhancing the electric field. Two permittivity-near-zero objects of simple shapes, namely, a thin cylindrical shell and a long thin rectangular bar, are chosen for numerical illustration. The enhancement of the electric field becomes stronger when the permittivity-near-zero object becomes thinner. The physical mechanism of the field enhancement is completely different from the plasmonic resonance enhancement at a metal surface

Propagation of optical excitations by dipolar interactions in metal nanoparticle chains

Dispersion relations for dipolar modes propagating along a chain of metal nanoparticles are calculated by solving the full Maxwell equations, including radiation damping. The nanoparticles are treated as point dipoles, which means the results are valid only for a/d <= 1/3, where a is the particle radius and d the spacing. The discrete modes for a finite chain are first calculated, then these are mapped onto the dispersion relations appropriate for the infinite chain. Computed results are given for a chain of 50-nm diameter Ag spheres spaced by 75 nm. We find large deviations from previous quasistatic results: Transverse modes interact strongly with the light line. Longitudinal modes develop a bandwidth more than twice as large, resulting in a group velocity that is more than doubled. All modes for which k_mode <= w/c show strongly enhanced decay due to radiation damping.Comment: 26 pages, 7 figures, 2 tables. to appear in Phys. Rev.

Force on a neutral atom near conducting microstructures

We derive the non-retarded energy shift of a neutral atom for two different geometries. For an atom close to a cylindrical wire we find an integral representation for the energy shift, give asymptotic expressions, and interpolate numerically. For an atom close to a semi-infinite halfplane we determine the exact Green's function of the Laplace equation and use it derive the exact energy shift for an arbitrary position of the atom. These results can be used to estimate the energy shift of an atom close to etched microstructures that protrude from substrates.Comment: 7 pages, 5 figure

Non-Linear Deformations of Liquid-Liquid Interfaces Induced by Electromagnetic Radiation Pressure

The idea of working with a near-critical phase-separated liquid mixture whereby the surface tension becomes weak, has recently made the field of laser manipulation of liquid interfaces a much more convenient tool in practice. The deformation of interfaces may become as large as several tenths of micrometers, even with the use of conventional laser power. This circumstance necessitates the use of nonlinear geometrical theory for the description of surface deformations. The present paper works out such a theory, for the surface deformation under conditions of axial symmetry and stationarity. Good agreement is found with the experimental results of Casner and Delville [A. Casner and J. P. Delville, Phys. Rev. Lett. {\bf 87}, 054503 (2001); Opt. Lett. {\bf 26}, 1418 (2001); Phys. Rev. Lett. {\bf 90}, 144503 (2003)], in the case of moderate power or a broad laser beam. In the case of large power and a narrow beam, corresponding to surface deformations of about 50 micrometers or higher, the theory is found to over-predict the deformation. Possible explanations of this discrepancy are discussed.Comment: RevTeX4, 19 pages, 4 figures. Sec. IIIB rewritten, 4 new references. To appear in Phys. Rev.

Associations between selected demographic, biological, school environmental and physical education based correlates, and adolescent physical activity

The study investigated associations between selected physical activity correlates among 299 adolescents (90 boys, age 12-14 years) from 3 English schools. Physical activity was assessed by self-report and accelerometry. Correlates represented biological, predisposing, and demographic factors as described in the Youth Physical Activity Promotion Model. Boys engaged in more self-reported (p &amp;lt; .01) and accelerometer assessed physical activity than girls (p = .02). Positive associations between sex (male), BMI, Perceived PE Ability, Perceived PE Worth, number of enrolled students, and physical activity outcomes were evident (p &amp;lt; .05). Schoolbased physical activity promotion should emphasize sex-specific enhancement of students&#039; perceived PE competence and enjoyment

Can a charged ring levitate a neutral, polarizable object? Can Earnshaw's Theorem be extended to such objects?

Stable electrostatic levitation and trapping of a neutral, polarizable object by a charged ring is shown to be theoretically impossible. Earnshaw's Theorem precludes the existence of such a stable, neutral particle trap.Comment: 11 pages, 1 figur