Light Propagation

In this paper a novel approach based on Asymptotic Iteration Method (AIM) is presented to solve analytically the light propagation through one-dimensional inhomogeneous slab waveguide. Practically implemented optical slab waveguides based on traditional techniques are usually inhomogeneous and numerical methods are used to obtain guided wave characteristics. In this work, we develop analytical method for modal analysis includes Eigen modes

The electrostriction contribution to the nonlinear refractive index in optical fiber was theoretically calculated and measured. Nonlinearity was induced directly by insertion of the optical fiber into an intense external electric field. With this technique both the Kerr and the electrostrictive contributions to the intensity dependence of the nonlinear refractive index in a step-index fiber were measured. Good agreement between

The world-wide problem of increasing light pollution is assessed through the development of global maps of the distribution of zenith sky brightness with a resolution of approximately 1 km. These maps are produced using satellite imagery which provides photometrically calibrated data over the surface of the Earth at night, combined with a model of light scattering in the atmosphere to calculate the sky brightness from a given location. High resolution upward flux data have been obtained from the Operational Linescan System carried by the Defense Meteorological Satellite Program satellite, an oscillating scan radiometer with low-light visible and thermal infrared imaging capabilities. Light propagation in the atmosphere was computed at sea level based on the modeling technique introduced by Garstang which account for Earth curvature, double scattering and extinction. The Atlas reveals that light pollution of the night sky is not confined, as commonly believed, to developed countries,...

In this paper, evolution of spot size of an intense laser beam in cold, underdense, magnetized plasma has been studied. The plasma is embedded in a uniform magnetic field perpendicular to both, the direction of propagation and electric vector of the radiation field. Nonlinear current density is set up and the source dependent expansion method is used to determine the evolution of the spot size of a laser beam having a Gaussian profile. It is shown that transverse magnetization of plasma enhances the self-focusing property of the laser beam leading to reduction in critical power required to self-focus the beam.

Metamaterials are artificial media that allow tailoring the macroscopic properties of light propagation by a careful choice of nanoplasmonic inclusions it is made of. A simple and versatile analytical model describing propagation of electro magnetic waves in metamaterials is suggested. The model is based on the secondary averaging procedure in full analogy with the ordinary one accepted for Maxwell equations, where the nanoplasmonic inclusions (typically referred to as metaatoms or metamolecules) are ...

When an intense laser pulse interacts with homogeneous plasma embedded in a transverse magnetic field, transverse current density oscillating with frequency twice that of the laser field is set up. This leads to generation of second harmonic radiation with significant conversion efficiency.

The origin and properties of the transverse non-reciprocal magneto-optical (nMO) effect were studied. The transverse nMO effect occurs in the case when light propagates perpendicularly to the magnetic field. It was demonstrated that light can experience the transverse nMO effect only when it propagates in the vicinity of a boundary between two materials and the optical field at least in one material is evanescent. The transverse nMO effect is pronounced in the cases of surface plasmons and waveguiding modes. The magnitude of the transverse nMO effect is comparable to or greater than the magnitude of the longitudinal nMO effect. In the case of surface plasmons propagating at a boundary between the transition metal and the dielectric it is possible to magnify the transverse nMO effect and the magneto-optical figure-of-merit may increase from a few percents to above 100%. The scalar dispersion relation, which describes the transverse MO effect in cases of waveguide modes and surface plasmons propagating in a multilayer MO slab, was derived.

We derive a new unidirectional evolution equation for photonic nanowires made of silica. Contrary to previous approaches, our formulation simultaneously takes into account both the vector nature of the electromagnetic field and the full variations of the effective modal profiles with wavelength. This leads to the discovery of new, previously unexplored nonlinear effects which have the potential to affect soliton propagation considerably. We specialize our theoretical considerations to the case of perfectly circular silica strands in air, and we support our analysis with detailed numerical simulations.

A comparative study of two biopolymer based fiber optic humidity sensors is presented in this paper. Sensing elements Agarose and Chitosan swells in the presence of water vapour and undergoes changes in refractive index and modulates the intensity of light propagating through a fiber with Agarose or Chitosan as cladding. Copyright © 2007 IFSA.

ABSTRACT The second harmonic spectrum of Cr2-O3 is studied in the 1.7-2.9 eV spectral range as a function of temperature. Below the Néel temperature TN=307.5 K a nonlinear electric susceptibility chieijk(c) appears, which changes sign under the time-reversal operation. The interference of this susceptibility with the time-invariant magnetic susceptibility chimijk(i) leads to a pronounced polarization dependence for circularly polarized light propagating along the optical axis. This gives a novel tool to study antiferromagnetic domains with opposite orientation of the order parameter.

A general form of a metric preserving all symmetries of a spherically symmetric gravitational field and angular momentum in spherical coordinates is obtained. Such metric may have g01(r) = 0. The Newtonian limit uniquely defines g00(r). Geodesic motion under such metric exactly reproduces the precession of a planetary orbit, periastron advance of a binary, deflection of light and Shapiro time delay if the determinant of the time-radial parts of the metric is −1. In this model, the total time for a radial round trip of light is as in the Schwarzschild model, but it allows for light rays to have different speeds propagating toward or from the massive object. The value of g01(r) could be obtained by measuring these speeds. All of these metrics do satisfy Einstein's field equations.

Modern astrometry is based on angular measurements at the micro-arcsecond level. At this accuracy a fully general relativistic treatment of the data reduction is required. This paper concludes a series of articles dedicated to the problem of relativistic light propagation, presenting the final microarcsecond version of a relativistic astrometric model which enable us to trace back the light path to its emitting source throughout the non-stationary gravity field of the moving bodies in the Solar System. The previous model is used as test-bed for numerical comparisons to the present one. Here we also test different versions of the computer code implementing the model at different levels of complexity to start exploring the best trade-off between numerical efficiency and the micro-arcsecond accuracy needed to be reached.

We investigate the performance of the method proposed in Part I of this paper in several situations of interest in diffuse optical imaging of biological tissues. Monte Carlo simulations were extensively used to validate the approximate scaling relationship between higher-order and first-order self moments of the generalized temporal point-spread function in semi-infinite and slab geometry. More specifically we found that in a wide range of cases the scaling parameters c1, c2, c3 [see Eq. (36) of Part I] lie in the intervals (1.48, 1.58), (3.1, 3.7), and (8.5, 11.5), respectively. The scaling relationships between higher-order and first-order self moments are useful for the calculation of the perturbation of a single defect in a straightforward way. Although these relationships are more accurate for inclusions of linear size less than ≈6mm, their performance is also studied for larger inclusions. A good agreement, to within ≈10%, was found between the perturbations of single an...