Source: http://aoot.osa.org/ol/abstract.cfm?uri=ol-41-15-3479
Timestamp: 2019-04-24 06:14:05+00:00

Document:
Angle-resolved spectral analysis of a multioctave high-energy supercontinuum output of mid-infrared laser filaments is shown to provide a powerful tool for understanding intricate physical scenarios behind laser-induced filamentation in the mid-infrared. The ellipticity of the mid-infrared driver beam breaks the axial symmetry of filamentation dynamics, offering a probe for a truly (3+1)-dimensional spatiotemporal evolution of mid-IR pulses in the filamentation regime. With optical harmonics up to the 15th order contributing to supercontinuum generation in such filaments alongside Kerr-type and ionization-induced nonlinearities, the output supercontinuum spectra span over five octaves from the mid-ultraviolet deep into the mid-infrared. Full (3+1)-dimensional field evolution analysis is needed for an adequate understanding of this regime of laser filamentation. Supercomputer simulations implementing such analysis articulate the critical importance of angle-resolved measurements for both descriptive and predictive power of filamentation modeling. Strong enhancement of ionization-induced blueshift is shown to offer new approaches in filamentation-assisted pulse compression, enabling the generation of high-power few- and single-cycle pulses in the mid-infrared.
A. Couairon and A. Mysyrowicz, Phys. Rep. 441, 47 (2007).
L. Berge, S. Skupin, R. Nuter, J. Kasparian, and J.-P. Wolf, Rep. Prog. Phys. 70, 1633 (2007).
S. Skupin, G. Stibenz, L. Bergé, F. Lederer, T. Sokollik, M. Schnurer, N. Zhavoronkov, and G. Steinmeyer, Phys. Rev. E 74, 056604 (2006).
A. V. Mitrofanov, A. A. Voronin, D. A. Sidorov-Biryukov, G. Andriukaitis, T. Flöry, A. Pugžlys, A. B. Fedotov, J. M. Mikhailova, V. Ya. Panchenko, A. Baltuška, and A. M. Zheltikov, Opt. Lett. 39, 4659 (2014).
J. Kasparian, M. Rodriguez, G. Méjean, J. Yu, E. Salmon, H. Wille, R. Bourayou, S. Frey, Y.-B. André, A. Mysyrowicz, R. Sauerbrey, J.-P. Wolf, and L. Wöste, Science 301, 61 (2003).
D. Kartashov, S. Ališauskas, A. Pugžlys, A. Voronin, A. Zheltikov, M. Petrarca, P. Béjot, J. Kasparian, J.-P. Wolf, and A. Baltuška, Opt. Lett. 37, 3456 (2012).
A. V. Mitrofanov, A. A. Voronin, D. A. Sidorov-Biryukov, A. Pugžlys, E. A. Stepanov, G. Andriukaitis, T. Flöry, S. Ališauskas, A. B. Fedotov, A. Baltuška, and A. M. Zheltikov, Sci. Rep. 5, 8368 (2015).
A. V. Mitrofanov, A. A. Voronin, S. I. Mitryukovskiy, D. A. Sidorov-Biryukov, A. Pugžlys, G. Andriukaitis, T. Flöry, E. A. Stepanov, A. B. Fedotov, A. Baltuška, and A. M. Zheltikov, Opt. Lett. 40, 2068 (2015).
A. V. Mitrofanov, A. A. Voronin, D. A. Sidorov-Biryukov, S. I. Mitryukovsky, A. B. Fedotov, E. E. Serebryannikov, D. V. Meshchankin, V. Shumakova, S. Alisauskas, A. Pugzlus, V. Ya. Panchenko, A. Baltuska, and A. M. Zheltikov, Optica 3, 299 (2016).
D. Kartashov, S. Ališauskas, G. Andriukaitis, A. Pugžlys, M. Shneider, A. Zheltikov, S. L. Chin, and A. Baltuška, Phys. Rev. A 86, 033831 (2012).
M. Scheller, M. S. Mills, M. Miri, W. Cheng, J. V. Moloney, M. Kolesik, P. Polynkin, and D. N. Christodoulides, Nat. Photonics 8, 297 (2014).
P. A. Zhokhov and A. M. Zheltikov, Phys. Rev. Lett. 110, 183903 (2013).
S. C. Rae and K. Burnett, Phys. Rev. A 46, 1084 (1992).
L. Bergé, Opt. Express 16, 21529 (2008).
L. Bergé, J. Rolle, and C. Köhler, Phys. Rev. A 88, 023816 (2013).
Fig. 1. Experimental setup: GS, grism stretcher; GC, grating compressor; L, lenses; UV/Vis/NIR/MIR spec., spectrometers for spectral analysis in the UV, visible, near-IR, and mid-IR ranges; S, screen with a pinhole.
Fig. 2. (a) On-axis spectrum of supercontinuum radiation generated in a filament induced by the mid-IR OPCPA output in the air: (green) experiment, (blue) simulations. The spectrum of the mid-IR driver inducing the filament is shown with gray shading. (b)–(i) Far-field beam profiles of the supercontinuum output of the mid-IR filament: (b)–(e) experiments and (f)–(i) simulations. The filament is induced by 3.9 μm, 80 fs pulses with an energy of (b), (f) 4 mJ, (c), (g) 7 mJ, (d), (h) 11 mJ, and (e), (i) 17 mJ. The color scale encodes the normalized field intensity.
Fig. 3. Angle-resolved spectra of the supercontinuum output of the filament induced by 3.9 μm, 80 fs, 17 mJ driver pulses: (a) experiment and (b) simulations. Optical harmonics generated in the filament are labeled by numbers from 3 to 11, standing for the harmonic order. A letter “b” added to these numbers indicates the blueshifted component of the mth-order harmonic. The blueshifted off-axial components generated by the mid-infrared driver are labeled as 1b.
Fig. 4. (a) Longitudinal profile of the electron density in the filament. (b)–(e) Time-resolved beam dynamics calculated for different sections of the mid-infrared driver pulse, with τ = − 50 fs (b), − 25 fs (c), 0 fs (d), and 50 fs (e). (f) Results of simulations for the angle-resolved spectra of the supercontinuum output of the filament induced by 3.9 μm, 80 fs, 17 mJ driver pulses at different points z along the filament (as specified in the panels). (g)–(i) Temporal envelopes of field waveforms corresponding to spectral regions of 450–720 nm (g), 790–1150 nm (h), and 1500–4200 nm (i), contoured by dashed lines in panel (f) at z = 50.5 cm , with a compensation of a linear chirp of 40 fs 2 ( g , h ) and with phase compensation using 3 mm of BaF 2 (i).
(1) ∂ ∂ z A ˜ = [ i c 2 ω n 0 Δ ⊥ + i D ˜ ( ω ) ] A ˜ + F ˜ [ i ω 0 T ˜ c [ n 2 ( 1 − f R ) | A | 2 + f R ∫ − ∞ ∞ R ( t − t ′ ) | A ( t ′ ) | 2 d t ′ + n 4 | A | 4 ] A + i ω 0 μ 0 χ ( 3 ) T ˜ 4 n 0 2 A 3 − U i W ( I ) ( ρ 0 − ρ ) 2 I A ] − ( i ω 0 2 ω 2 c n 0 ρ c ( ω 2 + τ c − 2 ) + σ ( ω ) 2 ) F ˜ [ ρ ( t ) A ] .

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