Femtosecond and picosecond ultraviolet laser filaments in air: experiments and simulations

Tzortzakis, S.; Lamouroux, B.; Chiron, A.; Moustaizis, S.; Anglos, Demetrios; Michel, F. C.; Prade, B.; Mysyrowicz, A.

doi:10.1016/s0030-4018(01)01443-2

Cited by 65 publications

(43 citation statements)

References 26 publications

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“…UV filaments in air Figure 1.16 shows the case of a filamentation using a UV laser (248 nm) [86,87]. The intensity in an UV filament is lower, because multiphoton ionization only requires the simultaneous absorption of 3-4 photons; it occurs earlier during the collapse of the beam on its axis.…”

Section: Experimental Results On Pulse Self-shortening By Filamentationmentioning

confidence: 99%

“…Mikalauskas et al [56] showed by a measurement of third order autocorrelation that a pulse at 532 nm, with an initial duration of 900 fs, was shortened by a factor 6 after a propagation in the form of a filament over 16 m in air. Tzortzakis et al [87] have shown that ultraviolet picosecond pulses in the form of filaments are structured and strongly shortened. Couairon et al [18], by measuring cross-correlation traces between a pulse at the end of a filament and a non filamented pulse from the same laser (λ = 800 nm, duration 120 fs), report a temporal compression ratio of 10 for the self-guided pulse.…”

Section: Pulse Durationmentioning

confidence: 99%

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Femtosecond Filamentation in Air

Couairon

Mysyrowicz

2006

Springer Series in Chemical Physics

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Section: Experimental Results On Pulse Self-shortening By Filamentationmentioning

confidence: 99%

Section: Pulse Durationmentioning

confidence: 99%

Femtosecond Filamentation in Air

Couairon

Mysyrowicz

2006

Springer Series in Chemical Physics

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“…Femtosecond 248 nm laser pulses were generated using a XeCl excimer pumped dye laser system producing 450 fs pulses from a distributed feedback dye laser at 496 nm which, after frequency doubling, were amplified in the KrF excimer laser cavity. 18,19 The KrF cavity ͑Lambda-Physik EMG150MSC͒, operating unseeded, provided pulses of 15 ns full width at half maximum ͑FWHM͒ at 248 nm. The outputs of the nanosecond excimer laser and the frequency doubled dye laser had markedly different spatial profiles, beam divergences, and peak powers, which meant that these two sources produced very different spot sizes when focused at the target.…”

Section: Methodsmentioning

confidence: 99%

Dynamics of confined plumes during short and ultrashort pulsed laser ablation of graphite

et al. 2005

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The optical emission from electronically excited C species in the ablation plume following the short ͑ns͒ and ultrashort ͑fs͒ UV pulsed laser ablation of graphite is studied. Wavelength, time and spatially resolved imaging of the plume, in background pressures of inert gases such as argon and helium, is performed. Analysis of images of optical emission from C +* ions and C 2 * radicals, yielded estimates of the apparent velocity of emitting species, which appear to arise both from the initial ablation event and, in the presence of background gas, mainly from impact excitation. At elevated background pressures of argon ͑P Ar ͒, the formation and propagation of a shock wave is observed for ns pulses, whereas for fs pulses, the propagation of two shock waves is observed. During fs ablation, the first shock wave we associate with an initial burst of highly energetic/electronically excited ablated components, indicative of an enhanced fraction of non-thermal ejection mechanisms when compared with ns ablation. The second shock wave we associate with subsequently ejected, slower moving, material. Concurrent with the plume dynamics investigations, nanostructured amorphous carbon materials were deposited by collecting the ablated material. By varying P Ar from 5 to 340 mTorr, the film morphology could be changed from mirror smooth, through a rough nanostructured phase and, at the highest background pressures for ns pulses, to a low density cluster-assembled material. The evident correlations between the film structure, the mean velocities of the emitting C species, and their respective dependences upon P Ar are discussed for both pulse durations. In addition, we comment on the effect of observed initial plume dynamics on the subsequent C cluster formation in the expanding plume.

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“…Subpicosecond 248 nm laser pulses were generated using a XeCl excimer pumped dye laser system producing 450 fs pulses from a distributed feedback dye laser at 496 nm which, after frequency doubling, were amplified in the KrF excimer laser cavity. 22,23 The KrF cavity (LambdaPhysik EMG150MSC), operating unseeded, provided pulses of 15 ns full width at half maximum at 248 nm. The outputs of the nanosecond excimer laser and the frequency doubled dye laser had markedly different spatial profiles, beam divergences, and peak powers, which meant that these two sources produced very different spot sizes when focused at the target.…”

Section: Methodsmentioning

confidence: 99%

Comparing the short and ultrashort pulsed laser ablation of LiF

Henley¹,

Fuge²,

Ashfold³

2004

Journal of Applied Physics

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Pulsed laser ablation of LiF was studied using both nanosecond (ns) and femtosecond (fs) pulses at 248 nm. Optical emission from electronically excited Li and F atoms in the plume of ejected material was investigated by wavelength, time and spatially resolved imaging methods. Careful analysis of images of species selected optical emission yielded estimates of the mean velocities of the Li + ions arising in both excitation schemes (ϳ11 and ϳ13 km/ s, respectively), and highlighted the dramatic effects of radiation trapping, most notably by the reabsorption of Li͑2p → 2s͒ emission by ground state Li atoms in the ns ablation studies. Plumes formed by fs excitation are found to contain a higher fraction of energetic/electrically excited components, including excited F atoms and ions, indicative of an explosive boiling mechanism, whereas the ablation plume resulting from ns ablation is deduced to arise primarily from thermal evaporation of the transiently heated target surface. The amount of target material removed per shot is significantly less in the case of fs excitation. The density (and size) of unwanted droplets in films grown by fs ablation is much smaller than in the case of ns ablation, especially on substrates mounted in an off-axis ablation geometry, implying that hydrodynamic sputtering is much reduced by the use of short pulses and that fs ablation must be the preferred route to forming very thin LiF coatings.

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Femtosecond and picosecond ultraviolet laser filaments in air: experiments and simulations

Cited by 65 publications

References 26 publications

Femtosecond Filamentation in Air

Femtosecond Filamentation in Air

Dynamics of confined plumes during short and ultrashort pulsed laser ablation of graphite

Comparing the short and ultrashort pulsed laser ablation of LiF

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