Dramatic enhancement of supercontinuum generation in elliptically-polarized laser filaments

Rostami, Shermineh; Chini, Michael; Lim, Khan; Palastro, J. P.; Durand, Magali; Diels, Jean‐Claude; Arissian, Ladan; Baudelet, Matthieu; Richardson, Martin

doi:10.1038/srep20363

Cited by 35 publications

(10 citation statements)

References 34 publications

(72 reference statements)

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“…However, the change in the beams polarization itself as a result of its collapse remains largely unexplored. Since several applications of laser filamentation including HHG, THz generation and supercontinuum generation are polarization sensitive [38][39][40], investigating the polarization state of collapsing beams is crucial [41][42][43]. In some of the studies, molecular alignment and delayed birefringence acting on the probe were investigated [44][45][46].…”

Section: Introductionmentioning

confidence: 99%

Loss of polarization of elliptically polarized collapsing beams

et al. 2019

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We show theoretically and demonstrate experimentally that collapsing elliptically-polarized laser beams experience a nonlinear ellipse rotation that is highly sensitive to small fluctuations in the input power. For arbitrarily small fluctuations in the input power and after a sufficiently large propagation distance, the polarization angle becomes uniformly distributed in [0, 2π] from shot-toshot. We term this novel phenomenon loss of polarization. We perform experiments in fused-silica glass, nitrogen gas and water, and observe a significant increase in the fluctuations of the output polarization angle for elliptically-polarized femtosecond pulses as the power is increased beyond the critical power for self-focusing. We also show numerically and confirm experimentally that this effect is more prominent in the anomalous group-velocity dispersion (GVD) regime compared to the normal-GVD regime due to the extended lengths of the filaments for the former. Such effects could play an important role in intense-field light-matter interactions in which elliptically-polarized pulses are utilized.

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Section: Introductionmentioning

confidence: 99%

Loss of polarization of elliptically polarized collapsing beams

et al. 2019

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“…The intensity of the emission is determined by the gain and the continuum available to seed it, so it is important to consider the continuum in this context. Continuum generation strongly depends on laser ellipticity [32] and will influence the emission if the gain is not saturated. The continuum is highlighted in Figure 3(a), where the spectrum is separated into three regions: the ion emission at 428 nm, continuum next to the ion emission (431 -455 nm), and continuum far from the ion emission (479 -531 nm).…”

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Testing the Role of Recollision in N2+ Air Lasing

Britton

Laferrière

et al. 2018

Phys. Rev. Lett.

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It has been known for many years that during filamentation of femtosecond light pulses in air, gain is observed on the B to X transition in N_{2}^{+}. While the gain mechanism remains unclear, it has been proposed that recollision, a process that is fundamental to much of strong field science, is critical for establishing gain. We probe this hypothesis by directly comparing the influence of the ellipticity of the pump light on gain in air filaments. Then, we decouple filamentation from gain by measuring the gain in a thin gas jet that we also use for high harmonic generation. The latter allows us to compare the dependence of the gain on the ellipticity of the pump with the dependence of the high harmonic signal on the ellipticity of the fundamental. We find that gain and harmonic generation have very different behavior in both filaments and in the jet. In fact, in a jet we even measure gain with circular polarization. Thus, we establish that recollision does not play a significant role in creating the inversion.

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“…For instance, a strong backward stimulated radiation at 337 nm has been observed from a filament in nitrogen gas driven by a circularly polarized femtosecond laser pulse centered at 800 nm [19] . Filament-induced supercontinuum generation in molecular gases was dramatically enhanced in elliptically-polarized laser filaments [20] . Numerical simulations of the formation and development of filaments in argon with close to linear or circular polarization pulses [17] , polarization-dependent supercontinuum generation during filamentation [21] , and multiple filamentation suppression with circularly polarized pulses [22] have been reported.…”

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Polarization-dependent femtosecond laser filamentation in air

Zhu¹,

Wang²,

Liu³

et al. 2018

中国光学快报

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We report on a systematic study of the laser polarization effect on a femtosecond laser filamentation in air. By changing the laser's ellipticity from linear polarization to circular polarization, the onset position of laser filament formation becomes farther from the focusing optics, the filament length is shorter, and less laser energy is deposited. The laser polarization effect on air filaments is supported by a simulation and analysis of the polarization-dependent critical power and ionization rates in air.

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Dramatic enhancement of supercontinuum generation in elliptically-polarized laser filaments

Cited by 35 publications

References 34 publications

Loss of polarization of elliptically polarized collapsing beams

Loss of polarization of elliptically polarized collapsing beams

Testing the Role of Recollision in N2+ Air Lasing

Polarization-dependent femtosecond laser filamentation in air

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