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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.


Electric field of two-colour pulses composed from a 1030-nm fundamental and a 1370-nm () (a), 1400-nm () (b), or 1440-nm () (c) auxiliary component, with  and each a peak intensity of  () (red line). As a guide to the eye, the gray dashed lines shows the “envelope-term” of the two-colour few-cycle-pulse train. Superposed is a 515-nm component, with  and peak intensity  (blue line).
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f4: Electric field of two-colour pulses composed from a 1030-nm fundamental and a 1370-nm () (a), 1400-nm () (b), or 1440-nm () (c) auxiliary component, with and each a peak intensity of () (red line). As a guide to the eye, the gray dashed lines shows the “envelope-term” of the two-colour few-cycle-pulse train. Superposed is a 515-nm component, with and peak intensity (blue line).

Mentions: The enhanced gating with this third colour component is illustrated in Fig. 4 for different auxiliary wavelengths around the value of 1400 nm, which we had found to provide a good compromise between wide inter-pulse spacing of the few-cycle-pulse train and short few-cycle duration. On the scale of the individual few-cycle pulses, the -component functions as a “detuned second harmonic” of the carrier wave24, effectively “de-activating” all but a single half-cycle of the carrier wave for HHG. This doubles the periodicity of the CEP-dependence of HHG from (as in Fig. 3) to (see Fig. 5). On the time-scale of the “envelope-term” of the few-cycle-pulse train, the effect depends on . For integer (Fig. 4a,c), the -component has the same phase at every few-cycle-pulse maximum. Therefore, for odd , its phase relative to the carrier-wave of the few-cycle-pulse train is also the same at each few-cycle-pulse maximum, whereas it changes by from one few-cycle-pulse maximum to the next for even . This means that if for a given phase , for which the -component enhances HHG in the central few-cycle pulse, it will have a quenching effect in the adjacent few-cycle-pulses if the auxiliary wavelength is chosen such that is even. This is obviously beneficial for temporal gating since it effectively results in the generation of an IAP only every other few-cycle pulse in the train.


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)

Electric field of two-colour pulses composed from a 1030-nm fundamental and a 1370-nm () (a), 1400-nm () (b), or 1440-nm () (c) auxiliary component, with  and each a peak intensity of  () (red line). As a guide to the eye, the gray dashed lines shows the “envelope-term” of the two-colour few-cycle-pulse train. Superposed is a 515-nm component, with  and peak intensity  (blue line).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Electric field of two-colour pulses composed from a 1030-nm fundamental and a 1370-nm () (a), 1400-nm () (b), or 1440-nm () (c) auxiliary component, with and each a peak intensity of () (red line). As a guide to the eye, the gray dashed lines shows the “envelope-term” of the two-colour few-cycle-pulse train. Superposed is a 515-nm component, with and peak intensity (blue line).
Mentions: The enhanced gating with this third colour component is illustrated in Fig. 4 for different auxiliary wavelengths around the value of 1400 nm, which we had found to provide a good compromise between wide inter-pulse spacing of the few-cycle-pulse train and short few-cycle duration. On the scale of the individual few-cycle pulses, the -component functions as a “detuned second harmonic” of the carrier wave24, effectively “de-activating” all but a single half-cycle of the carrier wave for HHG. This doubles the periodicity of the CEP-dependence of HHG from (as in Fig. 3) to (see Fig. 5). On the time-scale of the “envelope-term” of the few-cycle-pulse train, the effect depends on . For integer (Fig. 4a,c), the -component has the same phase at every few-cycle-pulse maximum. Therefore, for odd , its phase relative to the carrier-wave of the few-cycle-pulse train is also the same at each few-cycle-pulse maximum, whereas it changes by from one few-cycle-pulse maximum to the next for even . This means that if for a given phase , for which the -component enhances HHG in the central few-cycle pulse, it will have a quenching effect in the adjacent few-cycle-pulses if the auxiliary wavelength is chosen such that is even. This is obviously beneficial for temporal gating since it effectively results in the generation of an IAP only every other few-cycle pulse in the train.

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.