Strong terahertz radiation generation by beating of two x-mode spatial triangular lasers in magnetized plasma

Abstract

Resonant THz radiation generation is proposed by beating of two spatial-triangular laser pulses of different frequencies (ω 1 , ω 2 ) and wave numbers ( k 1 , k 2 ) in plasma having external static magnetic field. Laser pulses co-propagating perpendicular to a dc magnetic field exert a nonlinear ponderomotive force on plasma electrons, imparting them an oscillatory velocity with finite transverse and longitudinal components. Oscillatory plasma electrons couple with periodic density ripples n ′ = n q0 e iqz to produce a nonlinear current, i.e., responsible for resonantly driving terahertz radiation at (ω = ω 1 − ω 2 , k = k 1 − k 2 + q). Effects of THz wave frequency, laser beam width, density ripples, and applied magnetic field are studied for the efficient THz radiation generation. The frequency and amplitude of THz radiation were observed to be better tuned by varying dc magnetic field strength and parameters of density ripples (amplitude and periodicity). An efficiency about 0.02 is achieved for laser intensity of 2 × 10 15 W/cm 2 in a plasma having density ripples about 30%, plasma frequency about 1 THz and magnetic field about 100 kG.

Benchmarking magnetised three-wave coupling for laser backscattering: analytic solutions and kinetic simulations

“…2007) and terahertz radiation generation (Varshney et al. 2015). In the parallel geometry, the electrostatic waves are unmagnetised but the right-handed (R) and left-handed (L) circularly polarised electromagnetic waves become non-degenerate, changing the coupling for Raman- and Brillouin-type scatterings (Sjölund & Stenflo 1967; Laham, Al Nasser & Khateeb 1998).…”

“…Most studies of MagLPIs so far are also restricted to special geometries where theories are greatly simplified. In the perpendicular geometry, X-wave pump lasers undergo backscattering (Paknezhad 2016;Shi, Qin & Fisch 2017a), forward scattering (Hassoon, Salih & Tripathi 2009;Babu et al 2021), second harmonics generation (Jha et al 2007) and terahertz radiation generation (Varshney et al 2015). In the parallel geometry, the electrostatic waves are unmagnetised but the right-handed (R) and left-handed (L) circularly polarised electromagnetic waves become non-degenerate, changing the coupling for Raman-and Brillouin-type scatterings (Sjölund & Stenflo 1967;Laham, Al Nasser & Khateeb 1998).…”

Terahertz radiation generation from short-pulse laser interaction with electron-hole plasmas

“…Two-dimensional amplitude modulated laser propagating in a ripple-density plasma can resonantly excite THz radiation at the modulation frequency [28]. Theoretical studies for THz radiation have been reported by considering the nonlinear mixing of two laser beams in plasmas that have beat frequency in the THz region [29][30][31]. However, in these previous studies, a gaseous plasma medium has been employed to excite the THz fields.…”

“…However, in these previous studies, a gaseous plasma medium has been employed to excite the THz fields. Varshney et al [29] have used the lasers beating in a gaseous plasma, where two lasers were employed for gaseous plasma interactions. In that study, an additional magnetic field was used for resonance, which can damage the semiconductor due to enormous J × B heating.…”