Third harmonic generation of a nonlinear laser Eigen mode of a self sustained plasma channel

Kumar, Kishan; Tripathi, V. K.

doi:10.1017/s0263034612000985

Cited by 3 publications

(1 citation statement)

References 33 publications

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“…To address these issues, plasma based THz emitters utilizing electron beams and laser plasma interaction were proposed such as coherent radiation from plasma oscillations driven by ultra-short laser pulses (Antonesen et al, 2006), synchrotron radiation from accelerated electrons (Liu et al, 2009), and transition radiation of electron beams (Sheng et al, 2004) etc. In these schemes, plasma as a nonlinear medium can handle very high power lasers with an added advantage of not having damage limit (Sheng et al, 2005;Kumar & Tripathi, 2013;Verma & Sharma, 2009;Giulietti et al, 1988;Panwar et al, 2013;Ghorbanalilu, 2012;Garg & Tripathi, 2010;Verma & Sharma, 2011).…”

Section: Introductionmentioning

confidence: 99%

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

Varshney

Sajal

Baliyan³

et al. 2014

Laser Part. Beams

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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.

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Section: Introductionmentioning

confidence: 99%

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

Varshney

Sajal

Baliyan³

et al. 2014

Laser Part. Beams

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Effects of transverse static electric field on terahertz radiation generation by beating of two transversely modulated Gaussian laser beams in a plasma

et al. 2014

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Resonant excitation of terahertz (THz) radiation by nonlinear coupling of two filamented spatial-Gaussian laser beams of different frequencies and wave numbers is studied in plasma having transverse static electric field. The static ponderomotive force due to filamented lasers is balanced by the pressure gradient force which gives rise to transverse density ripple, while, the nonlinear ponderomotive force at frequency difference of beating lasers couples with density ripple giving rise to stronger transverse nonlinear current which results into the excitation of THz radiation at resonance. The coupling is further enhanced by the presence of static electric field and spatial-Gaussian nature of laser beams. An increase of six-fold in the normalized amplitude of THz is observed by applying a direct current field of about 50 KV. Effects of frequency, laser beam width, and periodicity factor of modulated laser amplitude are studied for the efficient THz radiation generation. These results can be utilized for generating controlled tunable THz sources for medical applications using low filament intensities (~ 1014 W/cm2) of beating lasers.

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Step density model of laser sustained ion channel and Coulomb explosion

et al. 2015

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An analytical model of laser sustained ion channel in plasma is developed, assuming electron density to be zero in the inner region and constant outside. The radius of the channel is such that the ponderomotive force on electrons at the channel boundary is balanced by the channel space charge force. The laser is TM eigen mode of the system with Bessel function profile in the interior and modified Bessel function outside. The channel radius increases with laser intensity and the ratio of laser frequency to plasma frequency. Ion Coulomb explosion of the channel, on longer time scale, produces ion energy distribution, an increasing function of energy with a sharp cutoff equal to electron ponderomotive energy at the channel boundary. At peak laser intensity ≈2×1019W/cm2 at 1 μm wavelength and spot size of 8 μm, the cutoff ion energy in a plasma of density ∼1019cm−3 is ∼0.73 MeV.

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Third harmonic generation of a nonlinear laser Eigen mode of a self sustained plasma channel

Cited by 3 publications

References 33 publications

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

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

Effects of transverse static electric field on terahertz radiation generation by beating of two transversely modulated Gaussian laser beams in a plasma

Step density model of laser sustained ion channel and Coulomb explosion

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