Propagation-enhanced generation of intense high-harmonic continua in the 100-eV spectral region

Rivas, Daniel E.; Major, Balázs; Weidman, Matthew; Helml, Wolfram; Marcus, Gilad; Kienberger, Reinhard; Charalambidis, D.; Tzallas, P.; Balogh, Emeric; Kovács, Katalin; Toşa, V.; Bergues, Boris; Varjú, Katalin; Veisz, László

doi:10.1364/optica.5.001283

Cited by 24 publications

(17 citation statements)

References 47 publications

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“…In real experiments, if HHG works under the usual phase matching conditions, where the ionization is lower than the critical ionization rate (usually less than few percent) [37], the driving laser can be considered unmodified by the gas, and our conclusions are not affected by these effects. However, in the case of high ionization, the shape of the laser beam during propagation will be modified by the electrons in the medium [38][39][40][41], and the far-field shape of the laser beam profile is expected to change relevantly. In such cases, the ionization term must be included.…”

Section: Discussionmentioning

confidence: 99%

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High-flux 100-kHz attosecond pulse source driven by a high average power annular laser beam

Ye,

Oldal,

Csizmadia

et al. 2021

Preprint

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High-repetition-rate attosecond pulse sources are indispensable tools of time-resolved studies of electron dynamics, such as coincidence spectroscopy and experiments with high demands on statistics or signal-to-noise ratio, especially in case of solid and big molecule samples in chemistry and biology. Although with the high-repetition-rate lasers such attosecond pulses in a pump-probe configuration are possible to achieve, until now only a few such light sources have been demonstrated. Here, by shaping the driving laser to an annular beam, a 100-kHz attosecond pulse train (APT) source is reported with the highest energy so far (51 pJ/shot) on target (269 pJ at generation) among the systems using a laser with an average power in the 100 W regime and a repetition rate higher than 10 kHz. The on-target pulse energy is maximized by reducing the losses from the reflections and filtering of the high harmonics, and an unprecedented 19% transmission rate from the generation point to the target position is achieved. At the same time, the probe beam is also annular, and low loss of this beam is reached by using another holey mirror to combine with the APT. The advantages of using an annular beam to generate attosecond pulses with a high average power laser is demonstrated experimentally and theoretically.

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Section: Discussionmentioning

confidence: 99%

“…In our case, this method is valid when the nonlinear effect of the medium on the generation beam is not obvious. If the ionization rate is too high, the ionization term must be included in equation 2 [39,41].…”

Section: Theoretical Model For Beam Propagation Simulationmentioning

confidence: 99%

High-flux 100-kHz attosecond pulse source driven by a high average power annular laser beam

Ye,

Oldal,

Csizmadia

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…In real experiments, if HHG works under the usual phase matching conditions, where the ionization is lower than the critical ionization rate (usually less than a few percent) [71], the driving laser can be considered unmodified by the gas and our conclusions are not affected by these effects. However, in the case of high ionization, the shape of the laser beam during propagation will be modified by the electrons in the medium [33,[72][73][74] and the far-field shape of the laser beam profile is expected to change relevantly. To analyze the effect of ionization of the generation medium, we carried out additional simulations (see Section 3 in Supplementary Material for the details).…”

Section: Generation Beam (Xuv Arm)mentioning

confidence: 99%

High-Flux 100 kHz Attosecond Pulse Source Driven by a High-Average Power Annular Laser Beam

Oldal

Csizmadia

et al. 2022

Ultrafast Sci

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High-repetition rate attosecond pulse sources are indispensable tools for time-resolved studies of electron dynamics, such as coincidence spectroscopy and experiments with high demands on statistics or signal-to-noise ratio, especially in the case of solid and big molecule samples in chemistry and biology. Although with the high-repetition rate lasers, such attosecond pulses in a pump-probe configuration are possible to achieve, until now, only a few such light sources have been demonstrated. Here, by shaping the driving laser to an annular beam, a 100 kHz attosecond pulse train (APT) is reported with the highest energy so far (51 pJ/shot) on target (269 pJ at generation) among the high-repetition rate systems (>10 kHz) in which the attosecond pulses were temporally characterized. The on-target pulse energy is maximized by reducing the losses from the reflections and filtering of the high harmonics, and an unprecedented 19% transmission rate from the generation point to the target position is achieved. At the same time, the probe beam is also annular and low loss of this beam is reached by using another holey mirror to combine with the APT. The advantages of using an annular beam to generate attosecond pulses with a high-average power laser are demonstrated experimentally and theoretically. The effect of nonlinear propagation in the generation medium on the annular-beam generation concept is also analyzed in detail.

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“…Similarly, the dipole-induced phase mismatch has a complex spatial dependence through the variation of laser intensity with z (∆k d = α∂I 0 /∂z [46]). At the same time, it can be shown that for a guiding capillary [43], in case of a self-guided beam [21,47], or in experiments where loose focusing geometry is used (expressed as L med ≪ z R in a more quantitative form), this intensity variation is slow and the related phase-mismatch term can be neglected [4]. Also, when only short quantum trajectories are relevant, the proportionality constant α is small, and ∆k d ≈ 0 [4].…”

Section: Phase Matching Terms and Their Pressure Dependence In High-h...mentioning

confidence: 99%

Extended model for optimizing high-order harmonic generation in absorbing gases

Major,

Varjú

2021

Preprint

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We report on an extended version of the one-dimensional model proposed by Constant et al. [Phys. Rev. Lett 82(8), 1668] to study phase matching of high-order harmonic generation in absorbing and dispersive medium. The modelexpanded from zeroth to first order -can be used with media having a pressure profile varying linearly with propagation length. Based on the new formulas, the importance of having a generation medium that ends abruptly with a steep pressure gradient for achieving high flux is highlighted. In addition to further rule-of-thumb guidelines for harmonic-flux optimization, it is shown that having a steep increase of pressure in the beginning of the medium increases harmonic flux, while it also decreases the required medium length to reach the absorption-limited maximum.

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Propagation-enhanced generation of intense high-harmonic continua in the 100-eV spectral region

Cited by 24 publications

References 47 publications

High-flux 100-kHz attosecond pulse source driven by a high average power annular laser beam

High-flux 100-kHz attosecond pulse source driven by a high average power annular laser beam

High-Flux 100 kHz Attosecond Pulse Source Driven by a High-Average Power Annular Laser Beam

Extended model for optimizing high-order harmonic generation in absorbing gases

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