Optical trapping and manipulation of light-absorbing particles by means of a Hermite–Gaussian laser beam

This paper presents an analysis of the relativistic self-focusing of a rippled Gaussian laser beam in a plasma. Considering the nonlinearity as arising owing to relativistic variation of mass, and following the WKB and paraxial-ray approximations, the phenomenon of self-focusing of rippled laser beams is studied for arbitrary magnitude of nonlinearity. Pandey et al. [Phys. Fluids82, 1221 (1990)] have shown that a small ripple on the axis of the main beam grows very rapidly with distance of propagation as compared with the self-focusing of the main beam. Based on this analogy, we have analysed relativistic self-focusing of rippled beams in plasmas. The relativistic intensities with saturation effects of nonlinearity allow the nonlinear refractive index in the paraxial regime to have a slower radial dependence, and thus the ripple extracts relatively less energy from its neighbourhood.

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Influence of self-focused Laguerre-Gaussian laser beam on second harmonic generation in collisionless plasma having density transition

Optik ◽

10.1016/j.ijleo.2021.167747 ◽

2021 ◽

pp. 167747

Author(s):

Aman Bhatia ◽

Keshav Walia ◽

Arvinder Singh

Keyword(s):

Second Harmonic Generation ◽

Laser Beam ◽

Harmonic Generation ◽

Second Harmonic ◽

Collisionless Plasma ◽

Gaussian Laser Beam

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Generation of Efficient Terahertz Radiation by Relativistic Self-Focusing of A Cosh-Gaussian Laser Beam in A Magnetized Plasma

10.21203/rs.3.rs-1195824/v1 ◽

2021 ◽

Author(s):

Gunjan Purohit ◽

Bineet Gaur ◽

Pradeep Kothiyal ◽

Amita Raizada

Keyword(s):

Laser Beam ◽

Numerical Study ◽

The Self ◽

Magnetized Plasma ◽

Thz Radiation ◽

Gaussian Laser Beam ◽

Plasma Parameters ◽

Gaussian Profile ◽

Self Focusing ◽

Incident Laser Intensity

Abstract This paper presents a scheme for the generation of terahertz (THz) radiation by self-focusing of a cosh-Gaussian laser beam in the magnetized and rippled density plasma, when relativistic nonlinearity is operative. The strong coupling between self-focused laser beam and pre-existing density ripple produces nonlinear current that originates THz radiation. THz radiation is produced by the interaction of the cosh-Gaussian laser beam with electron plasma wave under the appropriate phase matching conditions. Expressions for the beamwidth parameter of cosh-Gaussian laser beam and the electric vector of the THz radiation have been obtained using higher-order paraxial theory and solved numerically. The self-focusing of the cosh-Gaussian laser beam and its effect on the generated THz amplitude have been studied for specific laser and plasma parameters. Numerical study has been performed on various values of the decentered parameter, incident laser intensity, magnetic field, and relative density. The results have also been compared with the paraxial region as well as the Gaussian profile of laser beam. Numerical results suggest that the self-focusing of the cosh-Gaussian laser beam and the amplitude of THz radiation increase in the extended paraxial region compared to the paraxial region. It is also observed that the focusing of the cosh-Gaussian laser beam in the magnetized plasma and the amplitude of the THz radiation increases at higher values of the decentered parameter.

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