Search results for "Polar"
showing 10 items of 3817 documents
Monte Carlo dosimetric characterization of the Cs-137 selectron/LDR source: evaluation of applicator attenuation and superposition approximation effe…
2004
The purpose of this study is to calculate the dose rate distribution for the Amersham Cs-137 pellet source used in brachytherapy with the Selectron low-dose-rate remote afterloading system in gynaecological applications using the Monte Carlo code GEANT4. The absolute dose rate distribution for the pellet source was obtained and presented as a one-dimensional absolute dose rate table as well as in the Task Group 43 dose-calculation formalism. In this study, excellent agreement was found between the point source theoretical model using fitted polynomial values and Monte Carlo calculations of the dose rate distribution for the pellet source. A comparison study was also made between the dose ra…
Influence of Multiple Scattering of the Intensity and Polarization of Diffuse Sky Radiation
1964
A physical explanation of the intensity and polarization of diffusion skylight in the plane of the sun’s vertical is attempted by an approximation method which takes into account the effects of multiple scattering. Various model atmospheres are considered. The scattered radiation field is assumed to be composed of (1) the scattered radiation due to the molecular atmosphere resulting from all orders of scattering; (2) the scattered radiation due to the turbid atmosphere including primary scattering only; and (3) the scattered radiation due to the turbid atmosphere resulting from secondary and higher-order scattering. The contribution due to the first term can be computed from the tables appl…
Collision-induced polarization scattering of dispersion managed solitons
2005
Using a multiscale expansion of coupled nonlinear Schrodinger equations we study the role of map strength and channel spacing for two colliding solitons. We numerically study then the depolarization caused by collisions of dispersion-managed vector solitons.
Phase conjugation in BaTiO 3 by use of the indirect photorefractive coupling of orthogonally polarized light waves
1998
A phase-conjugate wave is generated when an ordinary (extraordinary) signal wave is mixed with two counterpropagating extraordinary (ordinary) waves in the plane normal to the BaTiO3 polar axis. The photorefractive grating that couples the ordinary and the extraordinary waves appears if the incident waves induce a noticeable conical parametric scattering; this grating is a difference grating of many noisy scattering gratings recorded by means of the usual diffusion-mediated charge transport. For comparable intensities of signal and pump waves this type of nonlinear wave mixing is much more efficient than that which is due to the circular bulk photovoltaic effect.
Buildup of terahertz vector dark-soliton trains from induced modulation instability in highly birefringent optical fiber.
2007
We present the experimental observation of generation of vector dark-soliton pulse trains with terahertz repetition rates in the normal dispersion regime of an optical fiber. The polarization solitons build up from induced cross-phase modulation instability of two orthogonal pumps in a highly birefringent fiber.
Corrections to “Light Modulation Based on Fiber Cladding Mode Coupling Between Concatenated Long-Period Gratings” [Feb 1 152-154]
2011
In the above paper (ibid., vol. 23, no. 3, pp. 152-154, Feb. 1, 2011), there is an error in the eighth line of the abstract. The correct sentence is presented here.
Designed surface modes propagating along hyperbolic metamaterials
2013
We report on surface-wave propagation (SWP) that occurs in semi-infinite hyperbolic metamaterials whose optical axis is set in the interface plane. In practice it is implemented by a multi-layered metal-dielectric nanostructure that is cut normally to the layers. Our theoretical analysis shows that various conditions can be designed enabling distinct regimes of SWP. We concluded that hybridization of SWP polarization leads to tighter confinement near the interface as compared with conventional surface plasmon polaritons. By using the finite-element method (FEM), we demonstrate that the fields are enhanced on the walls of metallic films, and thus minimizing significantly its presence inside …
Near-field beam displacement at surface plasmon resonance
2011
International audience; A finite-size beam exciting a surface plasmon polariton (SPP) in a prism coupling configuration experiences an in-plane displacement that can be used for the characterization of plasmonic components by means of near-field optical microscopy. We first demonstrate experimentally the existence of this displacement by taking near-field images of finite-width metal strips. Next, the properties of this shift are analyzed in detail. We investigate the dynamic of the near-field shift for an incident Gaussian beam as a function of illumination conditions. For beams with a narrow spectrum, we propose a straightforward derivation showing that the displacement depends on the ave…
Counter-propagating difference frequency mixing in diamond with terahertz waves
2013
We investigate four-wave mixing between terahertz and optical pulses in diamond. We observe the occurrence of sum and difference frequency generation, with the latter being phase-matched for terahertz pulses counter-propagating to the optical field.
A broadband multifocal metalens in the terahertz frequency range
2016
Abstract Metasurfaces, the 2D form of metamaterials with their ability in phase, amplitude and polarization manipulation are widely used in designing optical devices. Efforts to find proper photonic components in the terahertz (THz) range of frequency lead us to adopt metasurfaces as their constituent elements. Here, we conceived a broadband THz lens with an adjustable number and arrangement of focal points. To have a full control over the lens functionality, we used a metasurface with the capability of simultaneously modulating the amplitude and phase of the incident wave. C-shaped ring resonators (CSRRs) with different geometry and orientation capable of simultaneously manipulating phase …