Post-filament self-trapping of ultrashort laser pulses

Mitrofanov, A. V.; Voronin, A. A.; Sidorov‐Biryukov, D. A.; Andriukaitis, G.; Flöry, Tobias; Pugžlys, Audrius; Федотов, А. Б.; Mikhailova, Julia M.; Panchenko, V. Ya.; Baltuška, Andrius; Желтиков, А. М.

doi:10.1364/ol.39.004659

Cited by 31 publications

(17 citation statements)

References 21 publications

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“…Our results imply the existence of new filamentation regimes due to intensity clamping at a Freeman resonance, especially for longer pulses of some 100 fs duration. This is in accordance with a recent experimental result which demonstrated that for 200fs pulses undergoing filamentation a "plasmaless" postfilament regime [26] emerges. However, while in former works, hypothetical plasmaless filaments were attributed to the HOKE, our research reveals a completely different underlying mechanism.…”

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confidence: 93%

Femtosecond filamentation by intensity clamping at a Freeman resonance

Hofmann

Brée

2015

Phys. Rev. A

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We demonstrate that Freeman resonances have a strong impact on the nonlinear optical response in femtosecond filaments. These resonances decrease the transient refractive index within a narrow intensity window and strongly affect the filamentation dynamics. In particular, we demonstrate that the peak intensity of the filament can be clamped at these resonances, hinting at the existence of new regimes of filamentation with electron densities considerably lower than predicted by the standard model. This sheds a new light on the phenomenon of filamentary intensity clamping and the plasmaless filaments predicted by the controversial higher-order Kerr model. PACS numbers: 32.80.Rm, 32.80.Xx, 42.65.Jx, 52.38.Hb Femtosecond laser filaments are narrow beams of intense laser light in ionizing media which maintain their beamwaist over distances exceeding the linear diffraction length [1]. The high optical intensities in filaments lead to transient refractive index modifications, and according to the established standard model of filamentation, they stem from an interplay of the all-optical Kerr effect and free electrons generated by multiphoton and tunneling ionization processes. Self-guided filaments are then understood to result from a balance of Kerr self-focusing and plasma defocusing [2]. While the temporal evolution of a filamentary laser pulse is highly dynamic and subject to recurrent focusing and refocusing cycles [3], a temporally averaged model can be shown to admit spatial soliton solutions, which produces the illusion of a nondiffracting beam [4,5].The standard model successfully fostered the theoretical understanding of various phenomena of nonlinear optics related to filamentation, like supercontinuum generation, pulse self-compression or terahertz generation [6][7][8]. However, it has recently been challenged by measurements of the cross-Kerr response in a pump-probe setup designed to detect the Kerr-induced birefringence [9]. This revealed strong deviations from the linear intensity dependence of the Kerr response, and led to the proposal of an extended model including higher-order terms in the intensity. Above a threshold intensity, these terms turn the Kerr response into a defocusing nonlinearity, leading to the prediction of plasmaless filaments [10]. The higher-order Kerr effect (HOKE) model has been heavyly debated [11][12][13][14][15]. Nevertheless, it turned out that some basic assumptions of the standard model should be reconsidered. One of the major weaknesses of the standard model appears now to be the fact that it mixes perturbative and nonperturbative aspects of nonlinear optics in an inadmissible manner. While the nonlinear polarization density is treated perturbatively, the typical intensities in filaments exceed the validity range of perturbative multiphoton ionization models. Instead, in order to correctly describe ionization effects, some variant of the nonperturbative Keldysh theory [16] is employed. The inadequacy of a perturbative description of the optical response in filaments has ...

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confidence: 93%

Femtosecond filamentation by intensity clamping at a Freeman resonance

Hofmann

Brée

2015

Phys. Rev. A

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“…A PCF with such a structure supports low-loss, anomalous-GVD guided modes (the solid line and grey shading in Fig. 1b) within the entire bandwidth covered by an output of mid-IR optical parametric amplifiers (OPAs) that have recently emerged as attractive sources for ultrafast strong-field nonlinear-optical studies in the mid-IR 36,37 . The broadband GVD anomaly provided by this fiber allows the entire spectrum of the sub-200-fs output of such OPA sources to be coupled into a soliton pulse inside the fiber.…”

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confidence: 99%

Sub-half-cycle field transients from shock-wave-assisted soliton self-compression

Voronin

Желтиков

2020

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We identify an unusual regime of ultrafast nonlinear dynamics in which an optical shock wave couples to soliton self-compression, steepening the tail of the pulse, thus yielding self-compressing soliton transients as short as the field sub-half-cycle. We demonstrate that this extreme pulse self-compression scenario can help generate sub-half-cycle mid-infrared pulses in a broad class of anomalously dispersive optical waveguide systems. Extremely short, subcycle electromagnetic field waveforms are rapidly emerging as powerful tools for ultrafast optics and photonic technologies 1-3 , enabling an unprecedented, subfemtosecond time resolution in laser spectroscopy 4,5 and an ultimate, subcycle precision in lightwave sculpting 6,7. Subcycle field waveforms are not unusual in terahertz technologies 8 , where such waveforms are generated as a result of optical rectification 9,10 , providing means for time-domain spectroscopy 11 , terahertz sensing 12 , and sub-quarter-cycle engineering 13. Terahertz field cycles are, clearly, too long to be relevant as probes for ultrafast dynamics in molecules, let alone the attosecond dynamics of electron wave packets and electron excitations in atoms and solids. Yet, the significance of the early work on subcycle terahertz field transients 8,9,14 is hard to overestimate-we owe it much of our understanding of fundamental properties of subcycle pulses and the universal tendencies in their unusual propagation dynamics. Optical methods of subcycle pulse generation rely on coherent field waveform synthesis 2 operating with high-order harmonics 15 , multiple Raman sidebands 16-19 , frequency-shifted supercontinua from hollow-core fibers 1,6 , and cascaded parametric amplification 20. As a promising alternative, anomalous-dispersion-assisted multioctave supercontinuum generation in solid materials 21 and guided-wave soliton self-compression (SSC) 22,23 can help create efficient sources of subcycle pulses covering a broad range of frequencies and peak powers. Here, we identify an unusual regime of ultrafast nonlinear dynamics in which an optical shock wave couples to soliton self-compression, steepening the tail of the pulse, thus yielding self-compressing soliton transients as short as the field sub-half-cycle. Optical shock waves are inevitable when the pulse duration of a field waveform approaches the field cycle 24. As their archetypical signature, optical shock waves tend to steepen the tail of the pulse, blue-shifting its spectrum 25. In special regimes of three-dimensional free-beam propagation, optical shock waves have been shown to force field waveforms to self-compress to subcycle pulse widths 26. Ordinarily, however, when building up via waveguide short-pulse evolution, optical shock waves do not lead to pulse shortening as a whole, giving rise to pulses with sharper trailing edges and asymmetric supercontinua. Still, our analysis presented in this paper shows that, when coupled to soliton self-compression an optical shock facilitates the generation of extraordinarily short field...

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“…Up to now, experiments on laser-induced filamentation in the atmospheric air (white circles in Fig. 1 ) were limited to the visible and near-infrared ranges ( λ < 1030 nm), where sufficiently powerful short-pulse laser sources were available 1 2 3 5 6 7 8 9 10 11 12 13 . Most of those earlier experiments on laser filamentation in the atmosphere were performed using Ti: sapphire laser systems 1 2 3 .…”

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“…1 ). However, building longer- λ alternatives to Ti: sapphire 1 2 3 and, since recently, ytterbium 9 and Cr: forsterite 10 lasers that would be capable of delivering ultrashort laser pulses with peak powers above P cr for the atmospheric air, i.e., at least a factor of λ 2 higher than the peak powers of amplified Ti: sapphire and ytterbium laser pulses used for atmospheric filamentation, is a challenging problem.…”

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Mid-infrared laser filaments in the atmosphere

Mitrofanov

Voronin

Sidorov‐Biryukov

et al. 2015

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159

136

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Filamentation of ultrashort laser pulses in the atmosphere offers unique opportunities for long-range transmission of high-power laser radiation and standoff detection. With the critical power of self-focusing scaling as the laser wavelength squared, the quest for longer-wavelength drivers, which would radically increase the peak power and, hence, the laser energy in a single filament, has been ongoing over two decades, during which time the available laser sources limited filamentation experiments in the atmosphere to the near-infrared and visible ranges. Here, we demonstrate filamentation of ultrashort mid-infrared pulses in the atmosphere for the first time. We show that, with the spectrum of a femtosecond laser driver centered at 3.9 μm, right at the edge of the atmospheric transmission window, radiation energies above 20 mJ and peak powers in excess of 200 GW can be transmitted through the atmosphere in a single filament. Our studies reveal unique properties of mid-infrared filaments, where the generation of powerful mid-infrared supercontinuum is accompanied by unusual scenarios of optical harmonic generation, giving rise to remarkably broad radiation spectra, stretching from the visible to the mid-infrared.

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Post-filament self-trapping of ultrashort laser pulses

Cited by 31 publications

References 21 publications

Femtosecond filamentation by intensity clamping at a Freeman resonance

Femtosecond filamentation by intensity clamping at a Freeman resonance

Sub-half-cycle field transients from shock-wave-assisted soliton self-compression

Mid-infrared laser filaments in the atmosphere

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