Relativistic-ponderomotive effects on cross-focusing of hollow Gaussian laser beams in plasma

AbstractThe present work aims to study the influence of relativistic–ponderomotive effects on cross-focusing of two co-propagating high-power hollow Gaussian laser beams [high-power laser beams (HGLBs)] in collisionless plasma. The effective dielectric constant has been derived on account of relativistic–ponderomotive nonlinearity. The phenomenon of cross-focusing for higher-order modes of HGLB is compared for the case when only relativistic nonlinearity is operative in the system and it is seen that the relativistic–ponderomotive effects make the focusing much stronger and relatively faster. The critical curves for various order of HGLB is discussed and compared with the case when only ponderomotive nonlinearity is present and it reveals that in the case of relativistic–ponderomotive case the spot size reduces effectively. The higher-order modes of propagation of HGLB are also found to be governed by the parameter of another propagating HGLB. The present study is useful in determining the propagation dynamics of HGLB.

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Electron plasma wave excitation by beating of two q-Gaussian laser beams in collisionless plasma

Laser and Particle Beams ◽

10.1017/s026303461500097x ◽

2016 ◽

Vol 34 (2) ◽

pp. 230-241 ◽

Cited By ~ 1

Author(s):

Arvinder Singh ◽

Naveen Gupta

Keyword(s):

Laser Beam ◽

Plasma Wave ◽

Electron Concentration ◽

Collisionless Plasma ◽

Electron Plasma ◽

Spot Size ◽

Laser Beams ◽

Plasma Parameters ◽

Electron Plasma Wave ◽

Ponderomotive Nonlinearity

AbstractThis paper presents a scheme for excitation of an electron-plasma wave (EPW) by beating two q-Gaussian laser beams in an underdense plasma where ponderomotive nonlinearity is operative. Starting from nonlinear Schrödinger-type wave equation in Wentzel–Kramers–Brillouin (WKB) approximation, the coupled differential equations governing the evolution of spot size of laser beams with distance of propagation have been derived. The ponderomotive nonlinearity depends not only on the intensity of first laser beam, but also on that of second laser beam. Therefore, the dynamics of one laser beam affects that of other and hence, cross-focusing of the two laser beams takes place. Due to nonuniform intensity distribution along the wavefronts of the laser beams, the background electron concentration is modified. The amplitude of EPW, which depends on the background electron concentration, is thus nonlinearly coupled with the laser beams. The effects of ponderomotive nonlinearity and cross-focusing of the laser beams on excitation of EPW have been incorporated. Numerical simulations have been carried out to investigate the effect of laser and plasma parameters on cross-focusing of the two laser beams and further its effect on EPW excitation.

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Design of large mode area all-solid anti-resonant fiber for high-power lasers

High Power Laser Science and Engineering ◽

10.1017/hpl.2021.7 ◽

2021 ◽

Vol 9 ◽

Author(s):

Xin Zhang ◽

Shoufei Gao ◽

Yingying Wang ◽

Wei Ding ◽

Pu Wang

Keyword(s):

High Power ◽

Single Mode ◽

Higher Order ◽

Coupling Scheme ◽

Resonant Coupling ◽

Higher Order Modes ◽

Mode Loss ◽

Fiber Mode ◽

Power Needs ◽

Mode Area

Abstract High-power fiber lasers have experienced a dramatic development over the last decade. Further increasing the output power needs an upscaling of the fiber mode area, while maintaining a single-mode output. Here, we propose an all-solid anti-resonant fiber (ARF) structure, which ensures single-mode operation in broadband by resonantly coupling higher-order modes into the cladding. A series of fibers with core sizes ranging from 40 to 100 μm are proposed exhibiting maximum mode area exceeding 5000 μm2. Numerical simulations show this resonant coupling scheme provides a higher-order mode (mainly TE01, TM01, and HE21) suppression ratio of more than 20 dB, while keeping the fundamental mode loss lower than 1 dB/m. The proposed structure also exhibits high tolerance for core index depression.

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