The effect of propagation in air on the filament spectrum

Arissian, Ladan; Mirell, Daniel; Rostami, Shermineh; Bernstein, Aaron; Faccio, Daniele; Diels, J.‐C.

doi:10.1364/oe.20.008337

Cited by 12 publications

(10 citation statements)

References 19 publications

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“…As the filament propagates through air and through the optical window, it undergoes significant temporal modulation and spectral broadening, as previously shown in numerical simulations and experimental measurements2930. We observed this broadening by inserting an uncoated wedge optic into the filament path at a grazing incidence and coupling the reflected light into a spectrometer.…”

Section: Resultssupporting

confidence: 64%

Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

Hartig

Ghebregziabher

Jovanovic

2017

Sci Rep

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The ability to perform not only elementally but also isotopically sensitive detection and analysis at standoff distances is impor-tant for remote sensing applications in diverse ares, such as nuclear nonproliferation, environmental monitoring, geophysics, and planetary science. We demonstrate isotopically sensitive real-time standoff detection of uranium by the use of femtosecond filament-induced laser ablation molecular isotopic spectrometry. A uranium oxide molecular emission isotope shift of 0.05 ± 0.007 nm is reported at 593.6 nm. We implement both spectroscopic and acoustic diagnostics to characterize the properties of uranium plasma generated at different filament-uranium interaction points. The resulting uranium oxide emis-sion exhibits a nearly constant signal-to-background ratio over the length of the filament, unlike the uranium atomic and ionic emission, for which the signal-to-background ratio varies significantly along the filament propagation. This is explained by the different rates of increase of plasma density and uranium oxide density along the filament length resulting from spectral and temporal evolution of the filament along its propagation. The results provide a basis for the optimal use of filaments for standoff detection and analysis of uranium isotopes and indicate the potential of the technique for a wider range of remote sensing applications that require isotopic sensitivity.

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Section: Resultssupporting

confidence: 64%

Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

Hartig

Ghebregziabher

Jovanovic

2017

Sci Rep

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“…4 is a clear evidence of seeding in the case of the beam with angular momentum. The larger seeding in the case of a beam with angular momentum is consistent with the observation that the white light is generated in the formation stage of the filament [28,29] where a larger distribution of wave vector can satisfy the group velocity or phase matching conditions of either x-waves [30,11] or four wave mixing. The polarization profile across the filaments with angular momentum [25] and interplay between the filaments can also play a role in four wave mixing and effective seeding at 428 nm.…”

supporting

confidence: 76%

Effect of rotational wave packets on the stimulated emission of nitrogen with light filament

Arissian

Kamer

Rasoulof

2016

Optics Communications

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“…Most experiments on N 2 + laser gain are conducted in long gas media in which the intense laser pulse modifies the optical properties of the medium, leading to self-focusing, filamentation, and the creation of long plasma channels. The complex propagation process is accompanied by the spectral, temporal, and spatial reshaping of the pump pulse [3,20], which leads to uncontrolled pumping conditions and possible self-probing (or self-seeding) of gain.…”

Section: Introductionmentioning

confidence: 99%

Short- and long-term gain dynamics in N2+ air lasing

et al. 2019

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Air lasing in the nitrogen molecular ion is not well understood because the complex physics responsible for gain is interwoven with pulse propagation in an extreme environment. Here we use a short gas jet to limit the interaction length, thereby removing the propagation effects. We report on several mechanisms that contribute to the decay of gain in different conditions, and experimentally isolate two decay timescales: the decay of long-term gain due to collisional state mixing, and short-term gain that cannot be explained by population inversion. To test the former, we control the inelastic electron scattering rate by varying the gas concentration while keeping the propagation length fixed, and predict the change of the decay using a model of collisional state mixing. We show that the same mechanism causes the decay of rotational wave packets in the states of the ion. Finally, we simulate the complex modulations of gain due to rotational wave packets and the propagation of the probe pulse through the evolving rotationally excited and inverted medium.

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The effect of propagation in air on the filament spectrum

Abstract: Filamentation studies traditionally start from letting a beam focus in air. We present filament studies with control over the preparation propagation, in air or vacuum, using an aerodynamic window. The spectral content of the filament strongly depends on its preparation medium.

Cited by 12 publications

References 19 publications

Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

Standoff Detection of Uranium and its Isotopes by Femtosecond Filament Laser Ablation Molecular Isotopic Spectrometry

Effect of rotational wave packets on the stimulated emission of nitrogen with light filament

Short- and long-term gain dynamics in N2+ air lasing

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