Tunable and efficient terahertz radiation generation by photomixing of two super Gaussian laser pulses in a corrugated magnetized plasma

Abstract

A scheme of terahertz (THz) radiation generation is investigated by photo-mixing of two super Gaussian laser beams having different frequencies (ω1, ω2) and wave numbers (k→1, k→2) in a performed corrugated plasma embedded with transverse dc magnetic field. Lasers exert a nonlinear ponderomotive force, imparting an oscillatory velocity to plasma electrons that couples with the density corrugations (n′=nα0eiαz) to generate a strong transient nonlinear current, that resonantly derives THz radiation of frequency ∼ωh (upper hybrid frequency). The periodicity of density corrugations is suitably chosen to transfer maximum momentum from lasers to THz radiation at phase matching conditions ω=ω1−ω2 and k→=k→1−k→2+α→. The efficiency, power, beam quality, and tunability of the present scheme exhibit high dependency upon the applied transverse dc magnetic field along with q-indices and beam width parameters (a0) of super Gaussian lasers. In the present scheme, efficiency ∼10−2 is achieved with the optimization of all these parameters.

Generation of electromagnetic waves in the terahertz frequency range by optical rectification of a Gaussian laser pulse in a plasma in presence of an externally applied static electric field

“…Any emitter based on these techniques cannot handle high power and breaks down because of the low damage threshold of the materials, whereas real‐time THz sensing and imaging as well as some nonlinear THz spectroscopy‐based instruments need efficient sources of high‐power THz waves . Plasma‐based emitters can be used for the generation of high‐power THz waves to avoid breakdown, as they can sustain very high power …”

“…In addition, various models have been developed for THz radiation generation by the interaction of high‐intensity laser beams with a preformed plasma . In a preformed plasma, two co‐propagating laser beams exert a nonlinear ponderomotive force on the electrons at the beat wave frequency ,. This ponderomotive force is directly proportional to the intensity of the laser beams.…”

“…The frequencies of the laser beams are selected in such a way that their difference falls in the THz range. Various intensity profiles have been used for THz frequency generation, such as Gaussian, supper Gaussian, cosh‐Gaussian, hollow Gaussian, triangular, etc . For resonant excitation and proper phase matching of the generated THz emission, a ripple density plasma with an appropriate wave vector has been used .…”

“…The effects of an externally applied magnetic field in both parallel and perpendicular directions have been investigated. It has been observed that the yield of the generated THz waves increases with the increase in magnitude of the externally applied magnetic field ,,,. Bhasin and Tripathi proposed a mechanism for the resonant excitation of THz frequency when an extraordinary‐mode picosecond laser pulse undergoes a process of optical rectification in a rippled density plasma in presence of an externally applied magnetic field .…”

Laser Intensity Profile Based Terahertz Field Enhancement from a Mixture of Nano-Particles Embedded in a Gas

“…Laser-plasma interaction can produce highly energetic and ultra-short THz fields. Laser-plasma based methods (Malik and Malik, 2011;Singh and Malik, 2014;Varshney et al, 2015;Varshney et al, 2018;Cho et al, 2015;Gurjar et al, 2020) have been used for high power THz emission in past few years as plasmas have no damage threshold limit. As laser technology progresses for higher peak intensities (Strickland and Mourou, 1985), THz peak power can be increased by scaling up the laser intensity.…”