scholarly journals Propagation of Vortex Hermite-Cosh-Gaussian Beams in a Gradient-Index Medium

2021 ◽  
Author(s):  
M. Lazrek ◽  
Z. Hricha ◽  
A. Belafhal
Keyword(s):  
Phase Distribution ◽  
Incident Beam ◽  
Propagation Distance ◽  
Gaussian Beams ◽  
Gradient Index ◽  
Output Beam ◽  
Propagation Equation ◽  
Intensity Pattern ◽  
Fiber Communications ◽  
Beam Parameters

Abstract Based on the Huygens–Fresnel integral, the propagation equation for a vortex Hermite-cosh-Gaussian beams (vHChGB) in gradient-index medium (GIM) is derived. From the obtained expression, the evolution of the intensity and the phase distributions of a vHChGB through a GIM are numerically demonstrated as a function of the gradient-index parameter β under the change of incident beam parameters. The results show that the characteristics of the output beam evolve periodically versus the propagation distance, and the period of evolution slows down when β is increased. Furthermore, it is demonstrated that the self-repeating properties of the intensity pattern and the phase distribution for the propagated vHChGB are altered by the incident beam parameters. The results obtained may be beneficial for applications in fiber communications and beam shaping.

scholarly journals Propagation Property of an Astigmatic sin–Gaussian Beam in a Strongly Nonlocal Nonlinear Media

2018 ◽  
Vol 9 (1) ◽  
pp. 71 ◽  
Author(s):  
Kaicheng Zhu ◽  
Jie Zhu ◽  
Qin Su ◽  
Huiqin Tang
Keyword(s):  
Light Field ◽  
Propagation Distance ◽  
Gaussian Beams ◽  
Propagation Property ◽  
Nonlinear Media ◽  
Phase Singularities ◽  
Nonlocal Nonlinear Media ◽  
Strongly Nonlocal Nonlinear Media ◽  
Beam Parameters ◽  
Nonlocal Nonlinear

Based on the Snyder and Mitchell model, a closed-form propagation expression of astigmatic sin-Gaussian beams through strongly nonlocal nonlinear media (SNNM) is derived. The evolutions of the intensity distributions and the corresponding wave front dislocations are discussed analytically and numerically. It is generally proved that the light field distribution varies periodically with the propagation distance. Furthermore, it is demonstrated that the astigmatism and edge dislocation nested in the initial sin-Gaussian beams greatly influence the pattern configurations and phase singularities during propagation. In particular, it is found that, when the beam parameters are properly selected, a vortex beam with perfect doughnut-shaped profile can be obtained for astigmatic sin-Gaussian beams with two-lobe pattern propagating in SNNM.

scholarly journals Behavior of the Central Intensity of Generalized Humbert-Gaussian Beams Against the Atmospheric Turbulence

2021 ◽  
Author(s):  
Naima Nossir ◽  
Latifa Dalil-Essakali ◽  
Abdelmajid Belafhal
Keyword(s):  
Atmospheric Turbulence ◽  
Intensity Distribution ◽  
Turbulent Atmosphere ◽  
Incident Beam ◽  
Paraxial Approximation ◽  
Gaussian Beams ◽  
Central Intensity ◽  
Fresnel Integral ◽  
Special Cases ◽  
Beam Parameters

Abstract Based on the generalized Huygens-Fresnel integral in the paraxial approximation and on the Rytov theory, the analytical expression of the axial intensity distribution for the Generalized Humbert-Gaussian beams (GHGBs) propagating through a turbulent atmosphere is derived in this work. The results for the special cases of GHGBs are deduced from our study and illustrated numerically. The influence of the turbulent strength and the incident beam parameters on the propagation of these beams in the atmospheric turbulence is investigated and discussed in detail.

Propagation Properties of Hollow Gaussian Beams in Gradient-Index Medium

2014 ◽  
Vol 51 (3) ◽  
pp. 032601
Author(s):  
黄永超 Huang Yongchao ◽  
黎昌金 Li Changjin ◽  
张新龙 Zhang Xinlong
Keyword(s):  
Gaussian Beams ◽  
Gradient Index ◽  
Propagation Properties

Influence of the active-medium inhomogeneity and of aperture stops on the output-beam parameters of a CO2laser

1982 ◽  
Vol 12 (5) ◽  
pp. 555-559
Author(s):  
V G Doronin ◽  
V I Novikov ◽  
V P Pipchenko ◽  
V A Stepanov
Keyword(s):  
Active Medium ◽  
Output Beam ◽  
Beam Parameters

HOLOGRAPHIC INVERSION OF DIFFUSE ELECTRON DIFFRACTION INTENSITIES FOR THE Ni(001)/K STRUCTURE

1994 ◽  
Vol 01 (02n03) ◽  
pp. 319-334 ◽  
Author(s):  
K. HEINZ ◽  
H. WEDLER
Keyword(s):  
Electron Diffraction ◽  
Lattice Gas ◽  
Three Dimensional ◽  
Incident Beam ◽  
Real Space ◽  
Reference Wave ◽  
Angle Of Incidence ◽  
Intensity Pattern ◽  
Diffuse Intensity ◽  
Adsorption Structure

At low temperatures many adsorbates arrange in lattice gas disorder on crystalline substrates. In a low energy electron diffraction (LEED) experiment this leads to diffuse intensities super-imposed on the sharp spots caused by the substrate. For the disordered adsorption system Ni(001)/K, we present two-dimensional intensity distributions as function of the electron energy and angle of incidence. They can be measured very fast (20 s per frame) and reliably using an automatic video based data acquisition technique. We show that diffuse intensity spectra DI(E) taken as function of energy for fixed surface parallel electron momentum transfer carry the information about the local adsorption structure. This is equivalent to conventional I(E) spectra taken for sharp spots. In the light of recent proposals it is shown that the diffuse single energy intensity pattern is not a hologram of the local structure because e.g. the reference wave is ill defined. However, the diffraction processes disturbing the pure reference wave cancel when the intensities of different energies are suitably averaged. It is demonstrated that the holographic reconstruction of real space information from such scanned energy data leads to reliable and well resolved atomic images. Full widths at half-maximum of such atomic images are not greater than 1 Å. Substrate atoms behind the reference atom in direction of the incident beam are imaged best. So, image reconstructions for different beam directions produce a full and high quality three-dimensional image of the local adsorption structure.

Design of Novel Beam Demagnifier Based on Total Reflection -Refraction

2011 ◽  
Vol 338 ◽  
pp. 22-25
Author(s):  
Hua Qin ◽  
Cun Zhi Sun
Keyword(s):  
Total Internal Reflection ◽  
Light Propagation ◽  
Extreme Points ◽  
Incident Beam ◽  
Apex Angle ◽  
Total Reflection ◽  
Propagation Characteristics ◽  
Output Beam ◽  
In Series ◽  
Tracing Method

A novel beam demagnifier(a cone) is presented based on total internal reflection-refraction principle, and the light propagation characteristics inside the cone were studied by using ray-tracing method and computer simulation. This paper presents several proof-theoretic results concerning a cone as a beam demagnifier under certain conditions. When the semiapex angle of the cone is equal to a series of specific values an output beam is parallel to an incident beam, the beam's diameter narrows, and the demagnification ratio of the cone is a function of apex angle and there exists a series of extreme points; the demagnifier can be used in series so as to further narrow or magnify the diameter of incident beam.

Characterizing flat-top laser beams using standard beam parameters

2006 ◽  
Vol 84 (3) ◽  
pp. 223-240 ◽  
Author(s):  
S Saghafi ◽  
M J Withford ◽  
Z Ghoranneviss
Keyword(s):  
Near Field ◽  
Analytical Models ◽  
Model Parameters ◽  
Fourth Moment ◽  
Output Beam ◽  
Field Versus ◽  
Kurtosis Parameter ◽  
Beam Characteristic ◽  
Padé Method ◽  
Beam Parameters

We examine the correspondence between various models describing flat-top laser beam profiles using two standard parameters; namely, the M2 factor and the kurtosis parameter. Numerical expressions for M2, based on the second moment of the beam irradiance distribution in the near and far fields and for the kurtosis parameter, k, based on the fourth moment at the near field, are obtained. Plots of k in the near field versus M2 demonstrate the similarities between the different analytical models used to describe flat-top profiles. Using the Padé approximation, a relationship between k and M2, a new reference formula, is derived that predicts the values of M2 to within less than a percent for these flattened beams. This method is then extended to define numerical expressions relating the beam parameters (i.e., M2 and k) and the parameters describing the beam characteristic in each analytical model (model parameters). The results obtained using the Padé method are used to describe the output beam profiles for a high power copper vapour laser fitted with an unstable resonator.PACS Nos.: 42.55.–f, 42.55.Lt, 42.60.–v

scholarly journals Development of reflection gratings for advanced ECRH scenarios

2019 ◽  
Vol 203 ◽  
pp. 04012
Author(s):  
Burkhard Plaum ◽  
Martin Schubert ◽  
Achim Zeitler ◽  
Walter Kasparek ◽  
Carsten Lechte ◽  
...  
Keyword(s):  
Plane Waves ◽  
Incident Beam ◽  
Interpolation Scheme ◽  
Reflection Gratings ◽  
Beam Parameters ◽  
3D Problem

An existing framework for the design of reflection gratings was reworked. It takes the astigmatic complex beam parameters and the orientations of the beam axes of the incident and reflected beams as input and synthesizes a grating, which transforms the incident beam into the reflected beam. This is done by decomposing the 3D problem into a series of 2D reflections of plane waves. The 2D grating profiles are optimized in parallel on multiple computers. Finally, the 3D grating is derived using a simplified interpolation scheme.

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