Self-Focusing of Hermite-Cosh-Gaussian Laser Beams in Plasma under Density Transition

Self-focusing of Hermite-Cosh-Gaussian (HChG) laser beam in plasma under density transition has been discussed here. The field distribution in the medium is expressed in terms of beam-width parameters and decentered parameter. The differential equations for the beam-width parameters are established by a parabolic wave equation approach under paraxial approximation. To overcome the defocusing, localized upward plasma density ramp is considered, so that the laser beam is focused on a small spot size. Plasma density ramp plays an important role in reducing the defocusing effect and maintaining the focal spot size up to several Rayleigh lengths. To discuss the nature of self-focusing, the behaviour of beam-width parameters with dimensionless distance of propagation for various values of decentered parameters is examined by numerical estimates. The results are presented graphically and the effect of plasma density ramp and decentered parameter on self-focusing of the beams has been discussed.

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Combined influence of axial electron temperature and exponential plasma density ramp on the self-focusing of a chirped laser in plasma

Zeitschrift für Naturforschung A ◽

10.1515/zna-2020-0021 ◽

2020 ◽

Vol 75 (7) ◽

pp. 671-675

Author(s):

Niti Kant ◽

Vishal Thakur

Keyword(s):

Electron Temperature ◽

Pulse Laser ◽

Plasma Density ◽

Beam Width ◽

Spot Size ◽

Higher Order ◽

The Self ◽

Chirped Pulse ◽

Self Focusing ◽

Paraxial Ray

AbstractAn analysis of the self-focusing of highly intense chirped pulse laser under exponential plasma density ramp with higher order value of axial electron temperature has been done. Beam width parameter is derived by using paraxial ray approximation and then solved numerically. It is seen that self-focusing of chirped pulse laser is intensely affected by the higher order values of axial electron temperature. Further, influence of exponential plasma density ramp is studied and it is concluded that self-focusing of laser enhances and occurs earlier. On the other hand defocusing of beam reduces to the great extent. It is noticed that the laser spot size reduces significantly under joint influence of the density ramp and the axial electron temperature. Present analysis may be useful for the analysis of quantum dots, the laser induced fusion and etc.

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The investigation of the features optical vortices focusing by ring gratings with the variable height using high-performance computer systems

Journal of Physics Conference Series ◽

10.1088/1742-6596/2086/1/012166 ◽

2021 ◽

Vol 2086 (1) ◽

pp. 012166

Author(s):

D A Savelyev

Keyword(s):

High Performance ◽

Focal Spot ◽

Fdtd Method ◽

Spot Size ◽

Laser Beams ◽

Optical Vortices ◽

Focal Spot Size ◽

Near Zone ◽

High Performance Computer ◽

Difference Time

Abstract The diffraction of vortex laser beams with circular polarization by ring gratings with the variable height was investigated in this paper. Modelling of near zone diffraction is numerically investigated by the finite difference time domain (FDTD) method. The changes in the length size of the light needle and focal spot size are shown depending on the type of the ring grating.

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On the exploration of graphical and analytical investigation of effect of critical beam power on self-focusing of cosh-Gaussian laser beams in collisionless magnetized plasma

Laser and Particle Beams ◽

10.1017/s0263034618000253 ◽

2018 ◽

Vol 36 (2) ◽

pp. 254-260 ◽

Cited By ~ 3

Author(s):

T. U. Urunkar ◽

S. D. Patil ◽

A. T. Valkunde ◽

B. D. Vhanmore ◽

K. M. Gavade ◽

...

Keyword(s):

Differential Equation ◽

Turning Points ◽

Beam Width ◽

Analytical Investigation ◽

Graphical Analysis ◽

Magnetized Plasma ◽

Laser Beams ◽

Beam Power ◽

Equation Approach ◽

Self Focusing

AbstractThe paper gives graphical and analytical investigation of the effect of critical beam power on self-focusing of cosh-Gaussian laser beams in collisionless magnetized plasma under ponderomotive non-linearity. The standard Akhmanov's parabolic equation approach under Wentzel–Kramers–Brillouin (WKB) and paraxial approximations is employed to investigate the propagation of cosh-Gaussian laser beams in collisionless magnetized plasma. Especially, the concept of numerical intervals and turning points of critical beam power has evolved through graphical analysis of beam-width parameter differential equation of cosh-Gaussian laser beams. The results are discussed in the light of numerical intervals and turning points.

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Optimizing laser focal spot size using self-focusing in a cone-guided fast-ignition ICF target

The European Physical Journal Plus ◽

10.1140/epjp/s13360-021-01488-8 ◽

2021 ◽

Vol 136 (5) ◽

Author(s):

Oriza Kamboj ◽

Harjit Singh Ghotra ◽

Vishal Thakur ◽

John Pasley ◽

Niti Kant

Keyword(s):

Focal Spot ◽

Spot Size ◽

Fast Ignition ◽

Focal Spot Size ◽

Self Focusing ◽

Laser Focal Spot ◽

Icf Target

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Relativistic Gaussian laser beam self-focusing in collisional quantum plasmas

Laser and Particle Beams ◽

10.1017/s0263034615000063 ◽

2015 ◽

Vol 33 (3) ◽

pp. 397-403 ◽

Cited By ~ 7

Author(s):

S. Zare ◽

S. Rezaee ◽

E. Yazdani ◽

A. Anvari ◽

R. Sadighi-Bonabi

Keyword(s):

Laser Beam ◽

Laser Energy ◽

Oscillation Amplitude ◽

Beam Width ◽

Spot Size ◽

Collisional Plasma ◽

Laser Spot ◽

Quantum Plasma ◽

Laser Spot Size ◽

Self Focusing

AbstractPropagation of Gaussian X-ray laser beam is presented in collisional quantum plasma and the beam width oscillation is studied along the propagation direction. It is noticed that due to energy absorption in collisional plasma, the laser energy drops to an amount less than the critical value of the self-focusing effect and consequently, the laser beam defocuses. It is found that the oscillation amplitude of the laser spot size enhances while passing through collisional plasma. For the greater values of collision frequency, the beam width oscillates with higher amplitude and defocuses in a shallower plasma depth. Also, it is realized that in a dense plasma environment, the laser self-focusing occurs earlier with the higher oscillation amplitude, smaller laser spot size and more oscillations.

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Self-focusing of asymmetric cosh-Gaussian laser beams propagating through collisionless magnetized plasma

Laser and Particle Beams ◽

10.1017/s0263034617000684 ◽

2017 ◽

Vol 35 (4) ◽

pp. 670-676 ◽

Cited By ~ 11

Author(s):

B. D. Vhanmore ◽

S. D. Patil ◽

A. T. Valkunde ◽

T. U. Urunkar ◽

K. M. Gavade ◽

...

Keyword(s):

Magnetic Field ◽

Ponderomotive Force ◽

Beam Width ◽

Magnetized Plasma ◽

Laser Beams ◽

Gaussian Beams ◽

Equation Approach ◽

Kutta Method ◽

Runge Kutta Method ◽

Self Focusing

AbstractIn this paper, self-focusing of asymmetric cosh-Gaussian laser beams in collisionless magnetized plasma has been studied. The non-linearity in dielectric constant considered herein is mainly due to the ponderomotive force. The non-linear coupled differential equations for the beam width parameters in transverse dimensions of the beam have been obtained by using WKB and paraxial approximations under parabolic equation approach. The numerical computation is completed by using fourth-order Runge–Kutta method. The effect of unlike decentered parameters in both transverse dimensions of the beam on self-focusing of cosh-Gaussian beams has been presented. Further, the effect of the static magnetic field and polarization modes of the laser has been explored.

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Sensitiveness of light absorption for self-focusing at laser–plasma interaction with weakly relativistic and ponderomotive regime

Laser and Particle Beams ◽

10.1017/s026303461600063x ◽

2016 ◽

Vol 34 (4) ◽

pp. 669-674 ◽

Cited By ~ 19

Author(s):

S.D. Patil ◽

M.V. Takale ◽

V.J. Fulari ◽

T.S. Gill

Keyword(s):

Laser Beam ◽

Light Absorption ◽

Beam Width ◽

Vital Role ◽

Equation Approach ◽

Gaussian Laser Beam ◽

Laser Plasma Interaction ◽

Self Focusing ◽

Plasma Density Distribution ◽

Relativistic Regime

AbstractIn the present paper, we have examined the sensitiveness of light absorption for self-focusing of Gaussian laser beam in plasma. By introducing dielectric function of plasma under ponderomotive and weakly relativistic regime, we have established the differential equation for beam-width parameter by using parabolic equation approach under Wentzel-Kramers-Brillouin and paraxial approximations and solved it numerically. In order to incorporate the sensitiveness of light absorption for self-focusing, behavior of normalized beam-width parameter; plasma density distribution with dimensionless distance of propagation is presented graphically and discussed. Numerical analysis shows that light absorption plays a vital role in self-focusing of laser beam in plasma under weakly relativistic and ponderomotive regime and gives reasonably interesting results.

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Growth of spike in relativistic Gaussian laser beam in a plasma and its effect on third-harmonic generation

Laser and Particle Beams ◽

10.1017/s0263034616000902 ◽

2017 ◽

Vol 35 (1) ◽

pp. 137-144 ◽

Cited By ~ 1

Author(s):

N. Ahmad ◽

S. T. Mahmoud ◽

G. Purohit

Keyword(s):

Laser Beam ◽

Beam Width ◽

Spot Size ◽

Main Beam ◽

Gaussian Laser Beam ◽

Third Harmonic ◽

Single Beam ◽

Self Focusing ◽

Diffraction Divergence ◽

Paraxial Ray

AbstractA paraxial ray formalism is developed to study the evolution of an on axis intensity spike on a Gaussian laser beam in a plasma dominated by relativistic and ponderomotive non-linearities. Ion motion is taken to be frozen. A single beam width parameter characterizes the evolution of the spike. The spike introduces two competing influences: diffraction divergence and self-convergence. The former grows with the reduction in spot size of the spike, while the latter depends on the gradient in non-linear permittivity. Parameter δ = (ωpr00/c) a00/(3.5 r00/r01) characterizes the relative importance of the two, where r01 and r00 are the spike and main beam radii, ωp is the plasma frequency, and a00 is the normalized laser amplitude. For δ > 1, the intensity ripple causes faster self-focusing of the beam; higher the ripple amplitude stronger the focusing. In the opposite limit, diffraction divergence increases more rapidly, slowing down the self-focusing of the beam. As the beam intensity rises due to self-focusing, it causes stronger generation of the third harmonic.

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Laser beam zooming and deflection using a nonlinear metamaterial refracting medium

EPJ Applied Metamaterials ◽

10.1051/epjam/2018003 ◽

2018 ◽

Vol 5 ◽

pp. 8

Author(s):

Andrew James Comley

Keyword(s):

Laser Beam ◽

Inertial Confinement Fusion ◽

Analytical Approach ◽

Focal Spot ◽

Spot Size ◽

Inertial Confinement ◽

Lower Intensity ◽

Focal Spot Size ◽

Confinement Fusion ◽

Nonlinear Metamaterial

In-process control of the focal spot size and pointing position of a laser as it interacts with a target (beam zooming and deflection) offers the possibility of unprecedented efficiency improvements in a number of applications, such as inertial confinement fusion and laser micromachining. Here is described a system in which the focussing characteristics of a laser beam at one wavelength can be controlled by a lower-intensity beam at another wavelength, via their mutual interaction with a nonlinear metamaterial refracting medium. Such a metamaterial approach permits the optical response of the medium to be tailored according to the wavelengths of interest and time response required in a given application. A metamolecule unit cell design is described in terms of an equivalent circuit based on a pair of LCR (inductance, capacitance, resistance) circuits coupled by a common nonlinear capacitor. The circuit is studied using an analytical approach to obtain an understanding of its properties and design relationships between circuit parameters. Potential realisations of the circuit are discussed.

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