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Enhanced multi-colour gating for the generation of high-power isolated attosecond pulses.

Haessler S, Balčiūnas T, Fan G, Chipperfield LE, Baltuška A - Sci Rep (2015)

Bottom Line: We present pulse characterization measurements of such auxiliary pulses generated directly by white-light seeded OPA with the required significantly shorter pulse duration than that of the fundamental.This, combined with our recent experimental results on three-colour waveform synthesis, proves that the theoretically considered multi-colour drivers for IAP generation can be realized with existing high-power laser technology.The high-energy driver pulses, combined with the strongly enhanced single-atom-level conversion efficiency we observe in our calculations, thus make multi-colour drivers prime candidates for the development of unprecedented high-energy IAP sources in the near future.

View Article: PubMed Central - PubMed

Affiliation: 1] Laboratoire d'Optique Appliqueé, ENSTA-Paristech, Ecole Polytechnique, CNRS, Université Paris-Saclay 91761 Palaiseau Cedex, France [2] Photonics Institute, Vienna University of Technology, Gußhausstraße 27/387, 1040 Vienna, Austria.

ABSTRACT
Isolated attosecond pulses (IAP) generated by high-order harmonic generation are valuable tools that enable dynamics to be studied on the attosecond time scale. The applicability of these IAP would be widened drastically by increasing their energy. Here we analyze the potential of using multi-colour driving pulses for temporally gating the attosecond pulse generation process. We devise how this approach can enable the generation of IAP with the available high-energy kHz-repetition-rate Ytterbium-based laser amplifiers (delivering 180-fs, 1030-nm pulses). We show theoretically that this requires a three-colour field composed of the fundamental and its second harmonic as well as a lower-frequency auxiliary component. We present pulse characterization measurements of such auxiliary pulses generated directly by white-light seeded OPA with the required significantly shorter pulse duration than that of the fundamental. This, combined with our recent experimental results on three-colour waveform synthesis, proves that the theoretically considered multi-colour drivers for IAP generation can be realized with existing high-power laser technology. The high-energy driver pulses, combined with the strongly enhanced single-atom-level conversion efficiency we observe in our calculations, thus make multi-colour drivers prime candidates for the development of unprecedented high-energy IAP sources in the near future.

No MeSH data available.


Waveform (zoom-in around pulse peak (a) or full pulse (b)) and driven quantum paths for IAP generation (a). The quantum paths, shown for the short-trajectory branches only, are represented by the real-parts of their ionization and recollision instants. These form matching pairs of curves, connected by arrows for the first of the shown driver sub-pulses. The colour of the data points shows on logarithmic scale the contribution of the corresponding quantum path to the generated HHG intensity. The blue-shaded energy-range marks the spectral filter used for the selecting an IAP in Fig. 5b.
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f6: Waveform (zoom-in around pulse peak (a) or full pulse (b)) and driven quantum paths for IAP generation (a). The quantum paths, shown for the short-trajectory branches only, are represented by the real-parts of their ionization and recollision instants. These form matching pairs of curves, connected by arrows for the first of the shown driver sub-pulses. The colour of the data points shows on logarithmic scale the contribution of the corresponding quantum path to the generated HHG intensity. The blue-shaded energy-range marks the spectral filter used for the selecting an IAP in Fig. 5b.

Mentions: The inner workings of the driver waveforms for optimal temporal gating and efficiency enhancement are well understood by studying the calculated quantum paths. Figure 6 shows the waveform and computed quantum paths corresponding to the results shown in Fig. 5b, i.e. for the even- auxiliary nm with and . The photon energies eV selected for the IAP are generated most efficiently only in a single event during the central driving sub-pulse. This event is launched by the strongest field crest (marked by the ionization instants), which is followed by a strong and broad field-crest efficiently accelerating the returning electron. The sub-pulse is short enough so that the sub-sequent field crest does only lead to much lower recollision energy and thus photon energy. The nearest adjacent sub-pulses have a different, sub-optimal cycle-shape leading to reduced ionization and subsequent electron-acceleration by the driving field. The next adjacent sub-pulses then repeat the cycle-shape of the central one, but the pulse envelopes reduce the peak field strengths so that the -eV photon energies are only reached with exponentially dropping trajectory contributions in the cutoff region.


Enhanced multi-colour gating for the generation of high-power isolated attosecond pulses.

Haessler S, Balčiūnas T, Fan G, Chipperfield LE, Baltuška A - Sci Rep (2015)

Waveform (zoom-in around pulse peak (a) or full pulse (b)) and driven quantum paths for IAP generation (a). The quantum paths, shown for the short-trajectory branches only, are represented by the real-parts of their ionization and recollision instants. These form matching pairs of curves, connected by arrows for the first of the shown driver sub-pulses. The colour of the data points shows on logarithmic scale the contribution of the corresponding quantum path to the generated HHG intensity. The blue-shaded energy-range marks the spectral filter used for the selecting an IAP in Fig. 5b.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4441196&req=5

f6: Waveform (zoom-in around pulse peak (a) or full pulse (b)) and driven quantum paths for IAP generation (a). The quantum paths, shown for the short-trajectory branches only, are represented by the real-parts of their ionization and recollision instants. These form matching pairs of curves, connected by arrows for the first of the shown driver sub-pulses. The colour of the data points shows on logarithmic scale the contribution of the corresponding quantum path to the generated HHG intensity. The blue-shaded energy-range marks the spectral filter used for the selecting an IAP in Fig. 5b.
Mentions: The inner workings of the driver waveforms for optimal temporal gating and efficiency enhancement are well understood by studying the calculated quantum paths. Figure 6 shows the waveform and computed quantum paths corresponding to the results shown in Fig. 5b, i.e. for the even- auxiliary nm with and . The photon energies eV selected for the IAP are generated most efficiently only in a single event during the central driving sub-pulse. This event is launched by the strongest field crest (marked by the ionization instants), which is followed by a strong and broad field-crest efficiently accelerating the returning electron. The sub-pulse is short enough so that the sub-sequent field crest does only lead to much lower recollision energy and thus photon energy. The nearest adjacent sub-pulses have a different, sub-optimal cycle-shape leading to reduced ionization and subsequent electron-acceleration by the driving field. The next adjacent sub-pulses then repeat the cycle-shape of the central one, but the pulse envelopes reduce the peak field strengths so that the -eV photon energies are only reached with exponentially dropping trajectory contributions in the cutoff region.

Bottom Line: We present pulse characterization measurements of such auxiliary pulses generated directly by white-light seeded OPA with the required significantly shorter pulse duration than that of the fundamental.This, combined with our recent experimental results on three-colour waveform synthesis, proves that the theoretically considered multi-colour drivers for IAP generation can be realized with existing high-power laser technology.The high-energy driver pulses, combined with the strongly enhanced single-atom-level conversion efficiency we observe in our calculations, thus make multi-colour drivers prime candidates for the development of unprecedented high-energy IAP sources in the near future.

View Article: PubMed Central - PubMed

Affiliation: 1] Laboratoire d'Optique Appliqueé, ENSTA-Paristech, Ecole Polytechnique, CNRS, Université Paris-Saclay 91761 Palaiseau Cedex, France [2] Photonics Institute, Vienna University of Technology, Gußhausstraße 27/387, 1040 Vienna, Austria.

ABSTRACT
Isolated attosecond pulses (IAP) generated by high-order harmonic generation are valuable tools that enable dynamics to be studied on the attosecond time scale. The applicability of these IAP would be widened drastically by increasing their energy. Here we analyze the potential of using multi-colour driving pulses for temporally gating the attosecond pulse generation process. We devise how this approach can enable the generation of IAP with the available high-energy kHz-repetition-rate Ytterbium-based laser amplifiers (delivering 180-fs, 1030-nm pulses). We show theoretically that this requires a three-colour field composed of the fundamental and its second harmonic as well as a lower-frequency auxiliary component. We present pulse characterization measurements of such auxiliary pulses generated directly by white-light seeded OPA with the required significantly shorter pulse duration than that of the fundamental. This, combined with our recent experimental results on three-colour waveform synthesis, proves that the theoretically considered multi-colour drivers for IAP generation can be realized with existing high-power laser technology. The high-energy driver pulses, combined with the strongly enhanced single-atom-level conversion efficiency we observe in our calculations, thus make multi-colour drivers prime candidates for the development of unprecedented high-energy IAP sources in the near future.

No MeSH data available.