The Experts below are selected from a list of 37827 Experts worldwide ranked by ideXlab platform

Ehud Heyman - One of the best experts on this subject based on the ideXlab platform.

  • Gaussian Beam summation analysis of half plane diffraction: A full 3D formulation
    2008 IEEE 25th Convention of Electrical and Electronics Engineers in Israel, 2008
    Co-Authors: Michael Katsav, Ehud Heyman
    Abstract:

    A Gaussian Beam summation (GBS) representation for a three-dimensional half-plane diffraction of a Gaussian Beam (GB) that hits arbitrarily close to the edge is presented. The expansion involves an angular spectrum of GB¿s in the plane normal to the edge and a discrete phase-space decomposition along the edge. The field is thus described as a sum of GB¿s emerging from a discrete set of points along the edge, at a discrete set of directions in a polar coordinate system. Expressions for the excitation amplitudes of the diffracted Beams are derived and validated numerically.

  • Gaussian Beam Summation Representation of a Two-Dimensional Gaussian Beam Diffraction by a Half Plane
    IEEE Transactions on Antennas and Propagation, 2007
    Co-Authors: Michael Katsav, Ehud Heyman
    Abstract:

    A Gaussian Beam summation (GBS) representation for half plane diffraction of an incident two dimensional Gaussian Beam (GB) that hits arbitrarily close to the edge is presented. The scattered field is expanded into an angular spectrum of GBs that emerge from the edge. We derive asymptotic expressions for the diffracted Beams amplitudes, that are valid uniformly as a function of the distance of the incident Beam from the edge and of the scattering Beams angles. In the limiting cases when the incident GB hits far from the edge, these expressions reduce uniformly to a geometrical optics model plus a weak edge diffractions due to the off-axis Beam field that hits the edge. Applications to GBS modeling of indoor propagation are discussed.

  • frame based Gaussian Beam summation method theory and applications
    Radio Science, 2003
    Co-Authors: Christine Letrou, Ehud Heyman, Delphine Lugara, Amir Shlivinski, Amir Boag
    Abstract:

    [1] A discrete phase-space Gaussian Beam summation representation for electromagnetic radiation from a planar source is presented. The formulation is based on the theory of frames and removes the inherent difficulties of the Gabor representation for both monochromatic and ultra wideband (UWB) fields. For monochromatic fields the frame-based representation leads to an efficient and flexible discrete Gaussian Beam representation with local and stable expansion coefficients. For UWB fields a novel scaling of the frame overcompleteness parameter is introduced, leading to a new expansion that utilizes a discrete frequency-independent set of Beams over the entire relevant spectrum. It is demonstrated that the isodiffracting Gaussian Beams provide the snuggest frame representation over the entire spectrum. The rules for choosing the “optimal” frame and Beam parameters for a given problem are discussed and demonstrated on application examples.

Yangkang Chen - One of the best experts on this subject based on the ideXlab platform.

  • Least-Squares Gaussian Beam Transform for Seismic Noise Attenuation
    IEEE Transactions on Geoscience and Remote Sensing, 2019
    Co-Authors: Juan Wu, Mi Zhang, Yangkang Chen
    Abstract:

    We propose a novel seismic noise attenuation approach based on least-squares Gaussian Beam transform (LSGBT). Gaussian Beam transform uses time-domain Gaussian Beam (TGB), which can be characterized by a particular location, arrival time, amplitude, slope, curvature, and width. We implement the local attributes such as Beam center, spacing, and width to perform Gaussian Beam decomposition. In this approach, we first introduce the plane-wave decomposition (PWD) theory to implement TGB decomposition of noisy seismic data and then apply data reconstruction. Unlike most state-of-theart algorithms, random noise is attenuated in the process of Gaussian Beam reconstruction. In the reconstruction records, the useful events are well preserved simultaneously removing random noise. Comparisons of experimental results on field data using traditional f -x deconvolution (FX Decon) and median filter (MF) methods are also provided, which suggest that our method achieves better denoising performance than FX Decon and MF methods. Taking into account that signal loss is sometimes unavoidable in almost all existing denoising methods. In addition to the signal-to-noise ratio (SNR) measurement, we also use local similarity as an efficient tool to evaluate denoising performance. A group of synthetic and field examples demonstrates the effectiveness of the proposed approach.

Hongxing Xu - One of the best experts on this subject based on the ideXlab platform.

  • optical forces on interacting plasmonic nanoparticles in a focused Gaussian Beam
    Physical Review B, 2008
    Co-Authors: Zhipeng Li, Mikael Kall, Hongxing Xu
    Abstract:

    We theoretically analyze optical forces on aggregates of metal nanoparticles in a focused Gaussian Beam by extending the generalized Mie theory, which includes higher order multipoles and retardation effects. For two interacting metallic particles, an attractive gradient force, mainly caused by multipole plasmon excitation, exists at short interparticle distances, while induced dipolar fields dominate for separations of the order of the particle radius R or larger. The long-range force component can be either attractive or repulsive depending on the phase of the induced dipoles, as determined by the illumination wavelength and the collective dipolar plasmon resonance. In particular, the repulsive force that occurs for illumination near the plasmon resonance wavelength can be so large that it overcomes the optical trapping effect of the Gaussian Beam.

Sailing He - One of the best experts on this subject based on the ideXlab platform.

Guoquan Zhou - One of the best experts on this subject based on the ideXlab platform.

  • propagation of a partially coherent hollow vortex Gaussian Beam through a paraxial abcd optical system in turbulent atmosphere
    Optics Express, 2012
    Co-Authors: Guoquan Zhou
    Abstract:

    The propagation of a partially coherent hollow vortex Gaussian Beam through a paraxial ABCD optical system in turbulent atmosphere has been investigated. The analytical expressions for the average intensity and the degree of the polarization of a partially coherent hollow vortex Gaussian Beam through a paraxial ABCD optical system are derived in turbulent atmosphere, respectively. The average intensity distribution and the degree of the polarization of a partially coherent hollow vortex Gaussian Beam in turbulent atmosphere are numerically demonstrated. The influences of the Beam parameters, the topological charge, the transverse coherent lengths, and the structure constant of the atmospheric turbulence on the propagation of a partially coherent hollow vortex Gaussian Beam in turbulent atmosphere are also examined in detail. This research is beneficial to the practical applications in free-space optical communications and the remote sensing of the dark hollow Beams.

  • Far-field divergence of vectorial structure of a Gaussian Beam
    Applied Physics B, 2010
    Co-Authors: Guoquan Zhou
    Abstract:

    In the far-field, the Gaussian Beam is composed of the TE and TM terms. Moreover, the TE and TM terms of a Gaussian Beam are orthogonal to each other. The analytical and concise expressions of the TE and TM terms are derived in the far-field. The expressions of the energy flux distributions of the TE term, the TM term, and the whole Gaussian Beam are also presented in the far-field. The ratios of the power of the TE and TM terms to that of the whole Gaussian Beam are examined in the far-field. Also, the far-field divergence angles of the TE term, the TM term, and the whole Gaussian Beam are derived without any approximation. The inverse of the product of the wavenumber and the Gaussian Beam waist is defined as the f-parameter. The influences of the linearly polarized angle and the f-parameter on the far-field divergence angles of the TE term, the TM term, and the whole Gaussian Beam are discussed in detail.