Terahertz generation by mixing of two super-Gaussian laser beams in collisional plasma

Abstract

Considering a realistic situation, where electron-neutral collisions persist in plasma, analytical calculations are carried out for the Terahertz (THz) radiation generation by beating of two Super-Gaussian (SG) lasers of index p. The competency of these lasers over Gaussian lasers is discussed in detail with respect to the effects of collision and beam width on the THz field amplitude and efficiency of the mechanism. A critical transverse distance of the peak of the THz field is defined that shows a dependence on the index of SG lasers. Although electron-neutral collisions and larger beam width lead to the drastic reduction in the THz field when the SG lasers are used in the plasma, the efficiency of the mechanism remains much larger than the case of Gaussian lasers. Moreover, the higher index SG lasers produce stronger and focused THz radiation.

Effects of the evolution of two cross‐focused Gaussian laser beams on the terahertz generation in thermal collisional plasma

“…We have numerically solved the set of Equations 11a-11c and Equation 19 for thorough examination of the laser beam propagation and THz field generation under different laser and plasma conditions. This makes a gradient in the refractive index of plasma and consequently causes the focusing of beam.…”

“…[8] Nonlinearity emerging through the high-intensity laser-plasma interactions such as filamentation (as a result of ponderomotive force) can be the base and origin of THz emission. By optimizing the index of SG lasers and the periodicity of density ripples, Singh et al [19] realized that more focused THz radiation at a desired position can be obtained. [13,14] So far, different laser and plasma conditions have been considered to obtain high-power and efficient THz radiation.…”

“…Moreover, analytical calculations in the case of beating of two Super-Gaussian (SG) lasers in a collisional plasma show that although electron-neutral collisions and larger beam width lead to a drastic reduction in the THz field, the efficiency of the mechanism remains much larger than the case of Gaussian lasers. By optimizing the index of SG lasers and the periodicity of density ripples, Singh et al [19] realized that more focused THz radiation at a desired position can be obtained. In addition to a variety of laser pulse shapes, the effects of external fields on the efficiency and power of THz radiation have been analysed too.…”

Terahertz radiation emission using plasma‐filled dielectric liner with the effects of pre‐modulated relativistic electron beam

“…Singh and Malik [33] analysed the contribution of a collisional plasma under the influence of a magnetic field on the efficiency and amplitude of the THz radiation.…”

On validity of paraxial theory for super-Gaussian laser beams propagating in a plasma

“…However, the super-Gaussian lasers have recently attracted the researchers all over the world [13][14][15][16][17] for their better extraction from saturated laser amplifiers, better nonlinear conversion for same peak intensity, and top-hat beams have a parabolic thermal lens which does not decrease beam quality. Due to this reason, it becomes vital to investigate the profile of super-Gaussian lasers when they tunnel ionize the gas and produce the plasma.…”