Terahertz generation via optical rectification of x-mode laser in a rippled density magnetized plasma

Abstract

A scheme of resonant terahertz radiation generation by the optical rectification of a picosecond laser pulse in rippled density magnetized plasma is examined. The x-mode laser pulse, propagating perpendicular to dc magnetic field, exerts a quasistatic ponderomotive force on electrons, imparting them a drift with finite transverse component. The drift velocity beats with the density ripple to produce a current, resonantly driving terahertz radiation at frequency comparable to the inverse pulse duration. The terahertz power scales as the square of density ripple amplitude and rises with magnetic field strength. In the case when magnetic field is azimuthal with appropriate r-dependence, the terahertz power has a ring shape intensity distribution. At laser intensity of ∼3×1015 W/cm2, in a 0.01% critical density plasma with 30 kG magnetic field and 30% density ripple, one may have power conversion efficiency of 0.04%.

Strong terahertz radiation by beating of spatial-triangular lasers in a plasma

“…It means the THz radiation is emitted with its largest intensity on the axis, showing that the present scheme of two triangular lasers is capable of producing radiations those can be more easily collimated in comparison with other schemes. 4,8,9,11,[14][15][16][17] The higher intensity at y ¼ 0 is attributed to the highest magnitude of the y-component of the ponderomotive forcef NL p at y ¼ 0, which generates largest oscillating current.…”

“…This density perturbation produces a space-charge potential / at the frequency x and wave number k, causing a linear density perturbation n L ¼ À v er Á ðr/Þ 4pe together with v e À x 2 p x 2 as the electric susceptibility of the plasma. 14 NL þ x 2 c 2 eẼ.…”

“…This gives rise to a stronger transient transverse current due to a sharp gradient in the laser field, and subsequently THz radiation is excited resonantly in the presence of a periodic density structure. The present scheme yields the THz field $10 5 kV/cm and the efficiency $10 À2 for the laser intensity $10 14 Terahertz (THz) radiation generation has become an exciting field of research due to its wide applications in material characterization, imaging, topography and remote sensing, 1 chemical and security identification, etc. 2,3 The researchers all over the world have been putting their efforts to achieve a THz radiation source with large electric field, [4][5][6][7][8][9][10][11][12][13][14][15][16][17] and several schemes have been proposed.…”

Effect of magnetic field on terahertz generation via laser interaction with a carbon nanotube array

“…optical rectification of a short pulse laser or a surface plasma wave, photoconduction, Cherenkov radiation, etc. [1][2][3][4][5][6][7][8][9]. Presently, there is an increased interest in employing metallic nanostructures and carbon nanotubes to generate THz radiations as these structures offer the advantage of compactness with reasonable efficiency.…”

Terahertz Emitters, Detectors and Sensors: Current Status and Future Prospects

“…The process of two-photon absorption not only influences efficiency of terahertz generation but also impacts the terahertz spectrum . THz generation via optical rectification of x-mode laser in a rippled density magnetized plasma has been demonstrated [Bhasin and Tripathi [Bhasin & Tripathi, 2009]. Fiber lasers are attractive as terahertz emitters because of their low cost, small size, high repetition rate, high pulse energy, and short pulse duration [Hoffmann et al, 2008].…”