Angular distribution of the terahertz radiation intensity from the plasma channel of a femtosecond filament

Panov, N. A.; Kosareva, O.G.; Andreeva, Vera; Savel’ev, A. B.; Uryupina, D. S.; Volkov, R. V.; Makarov, Vladimir; Shkurinov, A. P.

doi:10.1134/s0021364011110099

Cited by 40 publications

(22 citation statements)

References 17 publications

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“…9 Furthermore, since the quadrupoles are induced by ponderomotive forces within the plasma, a square dependence on laser energy is expected for THz radiation. 14,27 This is consistent with our observations,…”

supporting

confidence: 93%

“…To interpret the angular distribution and polarization of THz waves, we propose a model based on radiation from time-varying electric quadrupoles 26,27 generated by electrons moving in response to the ponderomotive force of the laser pulses. The electrons in the vicinity of the laser pulse are expelled to the outside of the laser-produced plasma by the ponderomotive force originating from the radial gradient of the electric field.…”

mentioning

confidence: 99%

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Enhancing the energy of terahertz radiation from plasma produced by intense femtosecond laser pulses

Jahangiri

Hashida

Tokita

et al. 2013

Applied Physics Letters

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Terahertz (THz) radiation from atomic clusters illuminated by intense femtosecond laser pulses is investigated. By studying the angular distribution, polarization properties and energy dependence of THz waves, we aim to obtain a proper understanding of the mechanism of THz generation. The properties of THz waves measured in this study differ from those predicted by previously proposed mechanisms. To interpret these properties qualitatively, we propose that the radiation is generated by time-varying quadrupoles, which are produced by the ponderomotive force of the laser pulse.

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supporting

confidence: 93%

mentioning

confidence: 99%

Enhancing the energy of terahertz radiation from plasma produced by intense femtosecond laser pulses

Jahangiri

Hashida

Tokita

et al. 2013

Applied Physics Letters

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“…Experiments have indicated that the THz pulse generated by the filament is highly directional. It has been explained by the off-axis phase matching [8,9]. In our current work, we have observed superluminal propagation of THz pulse during filamentation process.…”

supporting

confidence: 53%

Terahertz wave guiding by femtosecond laser filament in air

et al. 2014

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In this paper, superluminal propagation of terahertz (THz) pulse has been observed by investigating the THz waveform emitted from different length of filaments. Further numerical simulation has implied that a THz waveguide-like photonic structure may be formed in air, leading to the superluminal propagation of the THz pulse. The underlying physical mechanisms and the control techniques of this type THz generation method might be revisited based on our findings. It might also potentially open a new approach for long-distance propagation of THz wave in air.OCIS codes: (320.7090) Ultrafast lasers; (350.5400) Plasmas.Strong diffraction and energy attenuation due to water vapor absorption are major obstacles to expedite the application of terahertz (THz) technology in non-laboratory environments. Femtosecond laser filamentation in air, a unique nonlinear optical phenomenon being able to generate a long plasma channel, has been suggested to provide a solution to this problem [1]. And the plasma channel is often referred to as a "filament". However, the fundamental nature of the THz wave propagation during the filamentation is barely known. In our current work, we have observed superluminal propagation of THz pulse during filamentation process. It provides evidence that the THz pulse does not undergo nature diffraction during the filamentation in air. Simulation results have confirmed that nonuniform transverse distribution of the plasma density inside the filament will give rise to the formation a waveguidelike photonic structure at THz band, in which THz energy is strongly confined into a sub-wavelength scale. Fig. 1(a) schematically shows the experimental setup. A 1 mJ, 1 kHz, 800 nm, 50 fs (FWHM) Ti: sapphire laser pulse was focused by a f = 110 cm lens, creating a centimeter-scale long filament in air. The generated THz pulse was detected by a standard electric-optic sampling (EOS) setup [2]. Particularly, a Teflon plate, which has high transmission for THz, was put inside the filament at different distances during our experiment. It not only blocked the transmission of fundamental 800 nm light, but also interrupted the formation of plasma filament. Fig. 1. (a) A Teflon plate, which can be moved along the laser propagation direction in a step length of 0.5 mm, was inserted into the plasma column. (b) The recorded THz waveforms as a function of propagation distance. The dashed white line highlights the superluminal phenomenon.THz waveforms recorded as a function of the propagation distance z are presented in Fig. 1(b), which are essentially plotted in the time coordinate moving at group velocity of the probe beam (800 nm pulse). The propagation distances correspond to the inserting positions of the Teflon plate and z = 0 is identified as the position of the focusing lens. It could be seen that THz pulse retains the characteristic of single cycle. However, what impresses us mostly is that the maximum of the THz waveform moves significantly forward as the pulse propagates further. This trend is highlighted in Fig. 1(b...

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“…3) has not been theoretically predicted or experimentally observed for those mechanisms. 3,12 The observed four-lobed angular distribution is reminiscent of the radiation pattern expected from time-varying electric quadrupoles, 13,14 which are considered here to explain the whole angular distribution. Ponderomotive force originating from the gradient of the electric field acts on electrons near the laser pulse, expelling them from the laser-produced plasma in a direction parallel or perpendicular to the laser propagation direction.…”

mentioning

confidence: 69%

Intense terahertz emission from atomic cluster plasma produced by intense femtosecond laser pulses

Jahangiri

Hashida

Nagashima

et al. 2011

Applied Physics Letters

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Terahertz (THz) emission from argon cluster plasma, generated by intense femtosecond laser pulses in the energy range of 10–70 mJ, has been investigated. THz polarization, energy dependence, and angular distribution were measured to provide an initial discussion on the mechanisms of THz emission. THz pulses of much higher energy were generated from argon clusters than from argon gas, which indicates that plasma produced from atomic clusters holds considerable promise as an intense THz source.

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Angular distribution of the terahertz radiation intensity from the plasma channel of a femtosecond filament

Cited by 40 publications

References 17 publications

Enhancing the energy of terahertz radiation from plasma produced by intense femtosecond laser pulses

Enhancing the energy of terahertz radiation from plasma produced by intense femtosecond laser pulses

Terahertz wave guiding by femtosecond laser filament in air

Intense terahertz emission from atomic cluster plasma produced by intense femtosecond laser pulses

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