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Generation of terahertz radiation from beating of two intense cosh-Gaussian laser beams in magnetized plasma
摘要： An analytical and numerical study has been carried out for the generation of terahertz (THz) radiation by beating of two intense cosh-Gaussian laser beams (decentered Gaussian beams) in the rippled density magnetized plasma under the relativistic–ponderomotive regime. In this process, both laser beams exert a relativistic–ponderomotive force on plasma electrons at the beat frequency and impart them an oscillatory velocity in the presence of a static magnetic field. Due to coupling between this nonlinear oscillatory velocity with density ripple, nonlinear current is generated that excites the THz radiation at the different frequency. Higher-order paraxial-ray approximation (non-paraxial theory) has been used in this study. The effects of the decentered parameter, magnetic field, and density ripple on the THz radiation generation in ripple density magnetized plasma have been investigated. Further, the effect of beating of laser beams on the THz field amplitude and the efficiency of THz radiation have been studied. The amplitude and efficiency of the emitted radiation are found to be highly sensitive to the decentered parameter, magnetic field, and density ripple. It has been found that the amplitude and efficiency of the generated THz radiation increase significantly with increasing the values of decentered parameter, magnetic field, and density ripple.
关键词： relativistic–ponderomotive nonlinearity,magnetized plasma,cross-focusing,terahertz radiation,Cosh-Gaussian laser beams
更新于2025-09-11 14:15:04
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Effect of cross-focusing of two Laser beams on THz radiation in graphite nanoparticles with density ripple
摘要： The present work explores the study of terahertz (THz) wave generation by the cross-focusing of two Gaussian laser beams in a bulk medium containing graphite nanoparticles (NPs). This system acts as a nonlinear medium behaving like plasma. The ripple is applied on the density of NPs to increase the conversion efficiency. Using the perturbative technique, a wave equation is derived which describes the nonlinear interaction of the laser beam with NPs. The nonlinear current at THz frequency arises due to the ponderomotive force exerted on the electrons of graphite NPs by the incident laser beams in the presence of density ripple. Numerical results show that the normalized amplitude of the generated THz wave increases by 3.5 times with the consideration of the phenomenon of cross-focusing. The results show the enhancement in the efficiency of generated THz wave on application of density ripple, due to the fulfillment of the phase matching condition.
关键词： plasma,cross-focusing,nanoparticles,density ripple,THz radiation
更新于2025-09-11 14:15:04
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A mixture of vortex terahertz radiation generation in inhomogeneous plasma by considering pump depletion
摘要： An attempt to extend helical terahertz radiation generation based on pump depletion is presented here. By considering an upward plasma density ramp, such a reasonable extension is examined to improve the results. It is claimed that the output terahertz energy is saturated which is attributed to laser pump divergence. The saturation effect is enhanced by considering suitable laser and plasma parameters. The adjustable slope of the density ramp is an important parameter for tuning terahertz generation efficiency, which is restricted to the up and down limit. For the resonant excitation of terahertz radiation, the ripple wave number is suitably chosen to satisfy the phase matching condition. Furthermore, as plasma frequency increases and approaches beat frequency, terahertz generation efficiency increases. Various laser and plasma parameters are employed and we report an efficiency of the order of 5×10?3 for the current scheme.
关键词： Laguerre–Gaussian beam,plasma density ramp,pump depletion,terahertz radiation generation,cross-focusing
更新于2025-09-11 14:15:04