scholarly journals Self-compression of two co-propagating laser pulse having relativistic nonlinearity in plasma

2017 ◽  
Vol 35 (4) ◽  
pp. 722-729
Author(s):  
S. Kumar ◽  
P. K. Gupta ◽  
R. K. Singh ◽  
R. Uma ◽  
R. P. Sharma
Keyword(s):  
Laser Beam ◽  
Pulse Width ◽  
Pulse Compression ◽  
Group Velocity Dispersion ◽  
Refractive Index Profile ◽  
Intense Laser ◽  
Laser Beams ◽  
Critical Parameters ◽  
Beam Power ◽  
Laser Beam Intensity

AbstractThe study proposes a semi-analytical model for the pulse compression of two co-propagating intense laser beams having Gaussian intensity profile in the temporal domain. The high power laser beams create the relativistic nonlinearity during propagation in plasma, which leads to the modification of the refractive index profile. The co-propagating laser beams get self- compressed by virtue of group velocity dispersion and induced nonlinearity. The induced nonlinearity in the plasma broadens the frequency spectrum of the pulse via self-phase modulation, turn to shorter the pulse duration and enhancement of laser beam intensity. The nonlinear Schrodinger equations were set up for co-propagating laser beams in plasmas and have been solved in Matlab by considering paraxial approximation. The propagation characteristics of both laser beams inside plasma are divided into three regions through the critical divider curve, which has been plotted between pulse width τ01 and laser beam power P01. Based on the preferred value of critical parameters, these regions are oscillatory compression, oscillatory broadening, and steady broadening. In findings, it is observed that the compression of the laser beam depends on the combined intensity of both beams, plasma density, and initial pulse width.

scholarly journals The splitted beam profile of laser beam in the interaction of intense lasers with overdense plasmas

2011 ◽  
Vol 29 (2) ◽  
pp. 161-168 ◽  
Author(s):  
Xiongping Xia ◽  
Zebin Cai ◽  
Lin Yi
Keyword(s):  
Wave Equation ◽  
Laser Beam ◽  
Nonlinear Wave ◽  
Nonlinear Wave Equation ◽  
Beam Profile ◽  
Intensity Profile ◽  
Intense Laser ◽  
Laser Beam Intensity ◽  
Physical Conditions ◽  
Self Focusing

AbstractIn this paper, the interaction of intense lasers with overdense plasmas is investigated. Based on the modified nonlinear wave equation describing the interaction of intense laser and overdense plasmas in nonparaxial region, due to the influence of off-axis components a2 and a4 in nonparaxial region, we first find the three-splitted laser beam intensity profile, besides, discuss detailed the forming mathematic and some possible physical conditions of the single highly self-focusing beam profile, two-splitted beam, and three-splitted beam profile. In addition, we also investigate the influence of the parameters βE02 and ρ2 on splitted beam profiles.

scholarly journals Dipole–Dipole Broadening in the Selective Reflection of an Intense Laser Beam from the Interface between a Transparent Dielectric and a Dense Resonance Gas

JETP Letters ◽  
2021 ◽  
Vol 114 (9) ◽  
pp. 524-527
Author(s):  
A. A. Bobrov ◽  
S. A. Saakyan ◽  
V. A. Sautenkov ◽  
B. B. Zelener
Keyword(s):  
Laser Beam ◽  
Spectral Width ◽  
Beam Intensity ◽  
Intense Laser ◽  
Selective Reflection ◽  
Laser Beam Intensity ◽  
Excited Atoms ◽  
Saturation Intensity ◽  
Transparent Dielectric ◽  
Natural Mixture

The dipole–dipole broadening of the spectrum of the selective reflection of intense resonance light from the interface between a transparent dielectric and a gas of the natural mixture of Rb isotopes has been studied experimentally. The case of a high gas density where the Doppler broadening can be neglected has been investigated. It has been shown that dipole–dipole broadening is reduced with increasing the number density of excited atoms. When the laser beam intensity is much higher than the saturation intensity of a resonance transition, a significant broadening due to the very high laser beam intensity has not been observed in the reflection spectrum from the transparent dielectric/gas interface. The observed intensity dependence of the spectral width has been explained by the quenching collisions of the excited atoms with the interface.

scholarly journals Generation of Second Harmonics of Relativistically Self-Focused q-Gaussian Laser Beams in Underdense Plasma with Axial Density Ramp

2021 ◽  
Author(s):  
Naveen Gupta ◽  
Sandeep Kumar
Keyword(s):  
Laser Beam ◽  
Plasma Wave ◽  
Pump Beam ◽  
Second Harmonic ◽  
Fluid Model ◽  
Intense Laser ◽  
Laser Beams ◽  
Variational Theory ◽  
Plasma Parameters ◽  
Pump Frequency

Abstract An investigation on frequency doubling of intense laser beams through the phenomenon of second harmonic generation (SHG) in underdense plasmas has been presented. In order to increase the efficiency of S.H.G the density profile of plasma has been considered in the shape of upward ramp. When laser beam with frequency !0 propagates through plasma, it makes the plasma electrons to oscillate at pump frequency. These oscillations of plasma electrons in the presence of thermal velocity generate a plasma wave at frequency !0. The generated plasma wave beats with the pump beam to double its frequency. Variational theory has been adopted to find semi analytical solution of the wave equation for the slowly varying envelope of the laser beam. By using hydrodynamic fluid model of plasma, nonlinear current density for SHG has been obtained. Emphasis are put on investigation of the effect of various laser and plasma parameters on propagation dynamics of pump beam and the power of generated second harmonics.

An Experimental Study on Laser Annealing of Thin Silicon Layers

1988 ◽  
Vol 110 (2) ◽  
pp. 416-423 ◽  
Author(s):  
C. P. Grigoropoulos ◽  
R. H. Buckholz ◽  
G. A. Domoto
Keyword(s):  
Laser Beam ◽  
Laser Annealing ◽  
Crystalline Silicon ◽  
Silicon Layer ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Beam Power ◽  
Silicon Phase ◽  
Laser Beam Intensity ◽  
Thin Silicon

A laser annealing technique directed toward producing single crystalline silicon on substrates is studied. In this paper the laser-induced melting of thin silicon films is studied experimentally. Direct heating of thin silicon layers on substrates is shown to produce a variety of different silicon melting patterns. A systematic study of these phase change phenomena has been performed. The important parameters are: (1) the laser beam power, (2) the laser beam intensity distribution, and (3) the speed of the translating silicon layer. Unstable silicon phase boundaries break up to form regions where solid and melt silicon coexist. Complicated silicon phase boundary patterns are shown. The experimental results showed the occurrence of organized patterns of alternating solid and liquid silicon stripes for two-dimensional heating distributions. Finally, temperature fields for the experimental operating conditions are calculated using an enthalpy model.

scholarly journals Accurate calculation of radiation damping parameters in the interaction between very intense laser beams and relativistic electron beams

2014 ◽  
Vol 32 (3) ◽  
pp. 477-486 ◽  
Author(s):  
Alexandru Popa
Keyword(s):  
Electromagnetic Field ◽  
Laser Beam ◽  
Relativistic Electron ◽  
Electron Energy ◽  
Electron Beams ◽  
Radiation Reaction ◽  
Radiation Damping ◽  
Intense Laser ◽  
Laser Beams ◽  
Relativistic Electron Beams

AbstractWe prove that the radiation damping force and the rate of change of the damping energy, in the Landau-Lifshitz forms, in interactions between very intense laser beams and relativistic electron beams, are periodic functions of only one variable, that is the phase of the electromagnetic field. The property is proved without using any approximation, in the most general case, when the degree of polarization of the electromagnetic field, the initial phase of the incident field and the initial energy of the electron have arbitrary values. This property leads to a strong simplification of the calculation of the radiation reaction parameters and of their dependence on the initial electron energy and angular frequency of the laser beam. Our analysis is performed in the proper inertial system of the electron. The radiation reaction is significant for laser beam intensities of the order 1022 W/cm2, and for electron energy greater than 1 GeV. The calculations reveal limitations of the method of generating hard radiations by interactions between laser beams and relativistic electron beams.

scholarly journals Pulse-compression and self-focusing of Gaussian laser pulses in plasma having relativistic–ponderomotive nonlinearity

2017 ◽  
Vol 35 (3) ◽  
pp. 429-436 ◽  
Author(s):  
S. Kumar ◽  
P.K. Gupta ◽  
R.K. Singh ◽  
S. Sharma ◽  
R. Uma ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Pulse Compression ◽  
Group Velocity Dispersion ◽  
Beam Width ◽  
Laser Pulses ◽  
Oscillatory Behavior ◽  
Intense Laser ◽  
Beam Radius ◽  
Self Focusing ◽  
Ponderomotive Nonlinearity

AbstractThe mathematical model for the propagation of intense laser pulse in a plasma having Gaussian profile is investigated. The model has been formulated considering that the relativistic–ponderomotive nonlinearity dominates over other nonlinearities in the plasma. Model equation for self-compression and self-focusing properties of the laser pulse has been set up and solved by both semi-analytical and numerical methods. The result indicates that due to the effect of group velocity dispersion, diffraction of the laser pulse and the nonlinearity of medium, the pulse width parameter as well as beam width parameter of pulse gets focused at a different normalized distance, and hence the normalized intensity is also deferred at those points. Numerical simulation shows an oscillatory behavior of intensity during propagation in the plasma either having minimum beam radius (r0) or having minimum pulse duration (t0) depending on the normalized distance.

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