Air filaments and vacuum

Diels, Jean‐Claude; Yeak, Jeremy; Mirell, Daniel; Fuentes, Rodrígo; Rostami, Shermineh; Faccio, Daniele; Trapani, P. Di

doi:10.1134/s1054660x10090379

Cited by 21 publications

(17 citation statements)

References 10 publications

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“…The inset shows the polarization and temporal schemes of a pair of two color pulses parameters: beam diameter, divergence and pulse duration [17][18][19][20]. Recent work by the authors of this paper has been reported toward remote high energy THz generation from two-color filaments [14].…”

Section: Introductionmentioning

confidence: 92%

Molecular alignment control of terahertz emission from a two-color filament in air

et al. 2011

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We demonstrate a method to control the terahertz (THz) emission from a two-color filament in air based on molecular alignment due to rotational Raman excitation. By tuning the delay time between rotational Raman excitation and THz excitation around the air molecule revival time, a significant modulation of THz emission is observed. The phenomenon is attributed to molecular alignment induced refractive index change, resulting in the changes of the nonlinearity (χ(3)) in neutrals and laser intensities inside the filaments.

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Section: Introductionmentioning

confidence: 92%

Molecular alignment control of terahertz emission from a two-color filament in air

et al. 2011

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“…In the case of linearly polarized light focused in vacuum, the fluorescence rises and decays over approximately 30 cm. Measurements of the beam profile versus distance however shows the filament to conserve a constant diameter for more than 75 cm [4,22]. When the beam is filamented in air, the plot of fluorescence versus distance is receded by about 20 cm, which represents the difference between the linear and nonlinear focus.…”

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confidence: 99%

“…These properties lead to light filamentation, a situation where the nonlinear properties of air determine the propagation properties. While they have been investigated since their discovery in 1995 both in the IR [1] and the UV [2], their formation and nature are still the object of controversy [3,4].In strong field ionization the light polarization had been extensively investigated [5] and used to control recollision of the electron [6,7]. Recently [8] detailed measurements of current in argon and nitrogen at filament intensities showed a strong dependence on light polarization.…”

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confidence: 99%

“…In linear polarization, measurements of the beam profile versus distance from the aerodynamic window have indicated that filaments are produced in both vacuum and air pre-filament cases. These measurements employed for the first time a linear attenuator consisting of a coated glass at 89 o incidence (attenuation factor > 10 8 ) [4]. In all cases where a filament is produced, its radius (1/e 2 of the intensity, or FWHM/1.177) is measured to be w 0 = 250 µm.…”

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confidence: 99%

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Effect of Light Polarization on Plasma Distribution and Filament Formation

Arissian

Mirell

Yeak

et al. 2012

Springer Proceedings in Physics

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We show that, for 200 fs light pulses at 790 nm, the formation of filaments is strongly affected by the laser light polarization . Filamentation does not exist for a pure circularly polarized light, propagating in vacuum before focusing in air, while there is no difference for focusing the light in air or vacuum for linearly polarized light.PACS numbers: 42.65.Jx Beam trapping, self-focusing and defocusing; self-phase modulation, 42.25.Ja Polarization, 32.80.Fb Photoionization of atoms and ions For a laser beam of sufficient intensity, air itself is a nonlinear medium, having a complex intensity dependent index of refraction, nonlinear absorption, induced birefringence, and becoming a partially conductive medium. These properties lead to light filamentation, a situation where the nonlinear properties of air determine the propagation properties. While they have been investigated since their discovery in 1995 both in the IR [1] and the UV [2], their formation and nature are still the object of controversy [3,4].In strong field ionization the light polarization had been extensively investigated [5] and used to control recollision of the electron [6,7]. Recently [8] detailed measurements of current in argon and nitrogen at filament intensities showed a strong dependence on light polarization. Measurement presented here demonstrate the effect of light polarization in filament formation. This effect has not been clearly investigated previously, because of the difficulty in 1) ascertaining that the beam has the expected polarization at the point where filamentation starts [9] and 2) making polarization measurements of a high intensity filament. These difficulties relate to the fact that the filamentation study is not a chamber study like most of the strong field light-matter interactions. Although there had been evidence of polarization deformation of high intensity beam propagating in air [9], filaments are prepared over a long propagation distance in gases. In order to have a clear starting point and a well defined initial condition for the filament, we use an aerodynamic window to prepare the filament in vacuum before launching it in air. By focusing the beam in vacuum to the filament size, all pre-filament nonlinear effects are eliminated [10]. Given such initial condition no filament is generated with circularly polarized light prepared in vacuum, while filaments are observed with the same circularly polarized beam propagating in air in the pre-filamentation stage. For the linearly polarized light filaments persist in both cases of pre-propagation in air and vacuum, with filaments prepared in vacuum having 20 percent longer length.An infrared filament is an ideal object to study strong field light-matter interaction, in which light and matter have a mutual recordable effect on each other, resulting in a confinement of a laser beam in a few hundred micron diameter channel, over distance, in excess of the Rayleigh range for that beam size.For the few hundred fs long pulses intense enough to create a filament in air,...

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Pulse characterization during femtosecond laser filamentation in air by two-photon fluorescence measurement

Liu

Wen

et al. 2011

Appl. Phys. B

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Air filaments and vacuum

Cited by 21 publications

References 10 publications

Molecular alignment control of terahertz emission from a two-color filament in air

Molecular alignment control of terahertz emission from a two-color filament in air

Effect of Light Polarization on Plasma Distribution and Filament Formation

Pulse characterization during femtosecond laser filamentation in air by two-photon fluorescence measurement

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