scholarly journals Numerical simulation of magnetized jet creation using a hollow ring of laser beams

2019 ◽  
Vol 26 (2) ◽  
pp. 022902 ◽  
Author(s):  
Y. Lu ◽  
P. Tzeferacos ◽  
E. Liang ◽  
R. K. Follett ◽  
L. Gao ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Laser Beams

scholarly journals Topological Charge and Asymptotic Phase Invariants of Vortex Laser Beams

Photonics ◽  
2021 ◽  
Vol 8 (10) ◽  
pp. 445
Author(s):  
Alexey A. Kovalev ◽  
Victor V. Kotlyar ◽  
Anton G. Nalimov
Keyword(s):  
Numerical Simulation ◽  
Data Transmission ◽  
Topological Charge ◽  
Light Field ◽  
Observation Point ◽  
Laser Beams ◽  
Optical Data ◽  
Optical Signals ◽  
Asymptotic Phase ◽  
Ring Approximation

It is well known that the orbital angular momentum (OAM) of a light field is conserved on propagation. In this work, in contrast to the OAM, we analytically study conservation of the topological charge (TC), which is often confused with OAM, but has quite different physical meaning. To this end, we propose a huge-ring approximation of the Huygens–Fresnel principle, when the observation point is located on an infinite-radius ring. Based on this approximation, our proof of TC conservation reveals that there exist other quantities that are also propagation-invariant, and the number of these invariants is theoretically infinite. Numerical simulation confirms the conservation of two such invariants for two light fields. The results of this work can find applications in optical data transmission to identify optical signals.

Numerical simulation of sensorless adaptive phase correction of regular, vortical, and incoherent multimode laser beams

2017 ◽  
Vol 30 (2) ◽  
pp. 191-197
Author(s):  
V. A. Bogachev ◽  
S. G. Garanin ◽  
F. A. Starikov ◽  
R. A. Shnyagin
Keyword(s):  
Numerical Simulation ◽  
Phase Correction ◽  
Laser Beams ◽  
Multimode Laser

scholarly journals Thermal defocusing of intense hollow Gaussian laser beams in atmosphere

2013 ◽  
Vol 31 (3) ◽  
pp. 403-410 ◽  
Author(s):  
Ashutosh Sharma ◽  
Mahendra Singh Sodha ◽  
Shikha Misra ◽  
S.K. Mishra
Keyword(s):  
Numerical Simulation ◽  
Urban Environments ◽  
Laser Beams ◽  
Beam Power ◽  
Dimensionless Form ◽  
High Power Laser ◽  
Power Laser ◽  
Hollow Beam ◽  
Rural And Urban ◽  
Absorption Window

AbstractIn this paper, the authors have presented a paraxial theory for propagation of (1) Gaussian (2) dark hollow Gaussian high power laser beams in the atmosphere, considering the nonlinearity arising from the temperature variation along the wave-front. Specifically, the focusing parameter for both beams has been evaluated as a function of distance and initial beam power and width (corresponding to radiation of wavelengths 1.045 µ, 1.625 µ, and 2.141 µ in the water absorption window) for the maritime, desert, rural, and urban environments as modeled at NRL; the results have been presented in the dimensionless form. It is seen that in all four environments a dark hollow beam defocuses less than the corresponding Gaussian beam of same radius and power. It is suggested that this conclusion based on the paraxial theory be verified by numerical simulation.

scholarly journals Integrated numerical simulation of indirect laser-driven implosion for ICF

1998 ◽  
Vol 16 (1) ◽  
pp. 91-99 ◽  
Author(s):  
J. Ramirez ◽  
R. Ramis ◽  
J. Meyer-Ter-Vehn
Keyword(s):  
Numerical Simulation ◽  
Heat Conduction ◽  
Equations Of State ◽  
Radiation Transport ◽  
Laser Beams ◽  
Flux Limiter ◽  
Electron Heat ◽  
Hydrodynamic Evolution ◽  
Radiation Induced ◽  
Inverse Bremsstrahlung Absorption

A NIF-type hohlraum target (Lindl 1995; CEA 1995) is analyzed in an integrated calculation that uses last revision (4.2) of MULTI2D code (Ramis et al. 1992). The numerical simulation includes: Lagrangian mesh, tracking of laser beams, inverse bremsstrahlung absorption, 3D radiation transport, radiation-induced hydrodynamics of casing and window panes, and radiatively driven capsule implosion. Electron heat conduction (Spitzer with flux limiter), tabulated Equations of State (Sesame), and LTE opacities are also included. Detailed results on hydrodynamic evolution of the system, compression symmetry, and energy balance are also provided.

scholarly journals Topological charge of optical vortices devoid of radial symmetry

2020 ◽  
Vol 44 (4) ◽  
pp. 510-518
Author(s):  
A.A. Kovalev
Keyword(s):  
Numerical Simulation ◽  
Topological Charge ◽  
Radial Symmetry ◽  
Laser Beams ◽  
Beam Power ◽  
Optical Vortices ◽  
Phase Retardation ◽  
Beam Asymmetry ◽  
Angular Momenta ◽  
Theoretical Predictions

Here we theoretically obtain values of the topological charge (TC) for vortex laser beams devoid of radial symmetry: asymmetric Laguerre-Gaussian (LG) beams, Bessel-Gaussian (BG) beams, Kummer beams, and vortex Hermite-Gaussian (HG) beams. All these beams consist of conventional modes, namely, LG, BG, or HG modes, respectively. However, all these modes have the same TC equal to that of a single constituent mode n. Orbital angular momenta (OAM) of all these beams, normalized to the beam power, are different and changing differently with varying beam asymmetry. However, for arbitrary beam asymmetry, TC remains unchanged and equals n. Superposition of just two HG modes with the adjacent numbers (n, n+1) and with the phase retardation of (pi)/2 yields a modal beam with the TC equal to – (2n+1). Numerical simulation confirms the theoretical predictions.

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