Spatial coherence of trajectory-resolved higher-order harmonics generated from an argon-filled gas cell using single- and two-color laser pulses

Kumar, M.; Singhal, H.; Ansari, A.; Chakera, J. A.

doi:10.1103/physreva.102.043101

Cited by 2 publications

(5 citation statements)

References 41 publications

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“…It may be noted here that harmonics generated from the annular beam also have a near Gaussian profile. It can further be seen from figure 2(b) that, in case of the Gaussian laser beam, the spectrum of all the individual harmonic orders is split into two parts: a strong one (having less divergence) and a weak one (having more divergence), which corresponds to the short and long electron trajectory contributions, respectively [32,38]. In the case of the annular beam profile (figure 2(a)), the splitting of the harmonic orders is almost absent, and only strong harmonic orders (having less divergence) corresponding to the short trajectories are present.…”

Section: Resultsmentioning

confidence: 90%

“…Further, it has been observed that, in the case of the Gaussian beam, there is splitting in the harmonic spectra due to the contribution of both long as well as short electron trajectories, whereas in the case of the annular beam, it was absent and the harmonic emission is mostly dominated by the short trajectory. Thus, the annular beam also provides lower divergence and higher coherence in the harmonic spectra [32,38]. This study will be of interest in attosecond metrology as well as in coherent diffraction imaging where higher photon flux and coherence are required.…”

Section: Discussionmentioning

confidence: 94%

“…In a recent study on HHG from an argon-filled cell [32], it was observed that the laser-drilled orifice in the cell plays an important role in HHG. It is therefore essential to investigate the role of the laser-drilled orifice in the experimentally observed results.…”

Section: Phase-matching Analysis For Short and Long Electron Trajecto...mentioning

confidence: 99%

“…Next, in gas jets, the gas flows out from the nozzle in a perpendicular direction to the laser propagation, which results in a mild gas-density gradient in the laser propagation direction and hence one can safely ignore its effect. However, in a gas cell, the gas flows out from the cell through the two orifices, viz the entrance and exit orifice, drilled by the driving laser pulse in its propagation direction [32]. The effect of the density gradient in this case cannot be ruled out.…”

Section: Introductionmentioning

confidence: 99%

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The effect of gas-density gradient on high-harmonic generation from neon-filled cells using annular and Gaussian laser beams

Ansari¹,

Kumar²,

Singhal³

et al. 2022

J. Phys. B: At. Mol. Opt. Phys.

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An experimental study was performed to explore the effect of gas-density gradient in laser propagation direction on high-harmonic generation from neon-filled cells using a 50 fs annular and Gaussian Ti:sapphire laser beam. It was observed that, despite 20% lower power, the photon flux of the high-harmonics generated using an annular beam under optimum parameter conditions (∼2.5 × 1010 photons/sec for the 37th order in a 5 mm long cell) is on par with the maximum photon flux generated using a full Gaussian beam (∼2 × 1010 photons/sec for the 37th order in a 15 mm long cell). To elucidate the underlying mechanism for the experimental observation, a numerical simulation of the propagation of both the annular and Gaussian laser beams inside the cell was performed. The simulation was extended to estimate the high-harmonic intensity, after incorporating the effect of laser defocusing, the electron trajectory resolved phase-matching, and gas-density gradient. The dominant role of short electron trajectories was observed in the case of the annular beam, whereas, in the case of the Gaussian beam, a contribution of both short and long trajectories was found. Our analysis shows that, in neon-filled cells, the gas-density gradient present at the laser exit end of the cell plays a dominant role in achieving a high photon flux using an annular laser beam. Further, the annular beam not only provides a higher flux but also has lower divergence and higher coherence. This study will be useful in attosecond pulse metrology as well as in imaging applications viz coherent diffractive imaging.

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Section: Resultsmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 94%

Section: Phase-matching Analysis For Short and Long Electron Trajecto...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The effect of gas-density gradient on high-harmonic generation from neon-filled cells using annular and Gaussian laser beams

Ansari¹,

Kumar²,

Singhal³

et al. 2022

J. Phys. B: At. Mol. Opt. Phys.

Self Cite

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show abstract

“…As a consequence, the attosecond temporal profile varies along the propagation axis [24,26,33,34]. A scientific effort is therefore increasingly devoted to exploring and controlling the spatial properties of high-order harmonics and attosecond pulses [19,20,23,24,26,31,32,[34][35][36][37][38][39][40] which is the aim of the study presented here.…”

Section: Introductionmentioning

confidence: 99%

Chromatic aberrations correction of attosecond high-order harmonic beams by flat-top spatial shaping of the fundamental beam

et al. 2023

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Attosecond pulses created by high-order harmonic generation in gases often exhibit strong chromatic aberrations, arising from the broad bandwidth and the wavelength dependent nonlinear light matter interaction. When the driving laser intensity varies spatially, as for Gaussian driving beams, the apparent source position of the harmonics differs significantly from one order to the next, thus affecting the achievable intensity and duration of the attosecond pulses when they are focused on target. We show that these chromatic aberrations can be reduced by spatially shaping the fundamental beam to generate high-order harmonics with a driver having a flat-top profile inside the gas medium. By measuring both the intensity profile and wavefront for each harmonic in a plane, we access the XUV beam properties and investigate these properties near focus. We observe that controlling chromatic aberrations by flat-top spatial shaping strongly reduces the variation of the XUV spectrum on the beam axis during propagation and, in return, the longitudinal sensitivity of both the temporal profiles and the temporal shifts of the focused attosecond pulses.

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Spatial coherence of trajectory-resolved higher-order harmonics generated from an argon-filled gas cell using single- and two-color laser pulses

Cited by 2 publications

References 41 publications

The effect of gas-density gradient on high-harmonic generation from neon-filled cells using annular and Gaussian laser beams

The effect of gas-density gradient on high-harmonic generation from neon-filled cells using annular and Gaussian laser beams

Chromatic aberrations correction of attosecond high-order harmonic beams by flat-top spatial shaping of the fundamental beam

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