Focusing Properties of High-Order Harmonics

Hoflund, Maria; Peschel, Jasper; Plach, Marius; Dacasa, Hugo; Veyrinas, K.; Constant, Éric; Smorenburg, P.W.; Wikmark, Hampus; Maclot, Sylvain; Guo, Chen; Arnold, Cord L.; L’Huillier, Anne; Eng-Johnsson, Per

doi:10.34133/2021/9797453

Cited by 32 publications

(20 citation statements)

References 52 publications

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“…For instance, the contribution ratio of the shift current to drift current is 2:3 by analyzing the THz radiation mechanism of few-layer WSe 2 , and the shift current contribution to the THz radiation of MoS 2 can be modulated from 40% to 90% after decreasing the incident angle from −40° to 0° . In these scenarios, the linear and nonlinear optical effects are not coupled together, which can be readily separated via analyzing the experimental data. , However, it is difficult to distinguish different kinds of nonlinear photocurrents since they are often coupled with each other, and the interplay between the shift current and photon drag current has been less reported . These issues could be detrimental to the light-to-current conversion and consequently hinder the development of the next-generation optoelectronic devices.…”

Section: Introductionmentioning

confidence: 99%

Interplay between Ultrafast Shift Current and Ultrafast Photon Drag Current in Tellurium Nanotubes

Cao

Huang

et al. 2022

ACS Photonics

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Photocurrent induced by nonlinear optical effects has innovated fundamental optic physics in optoelectronic devices, including nonlinear photodetectors, nonlinear optical absorbers, and solar cells. The cooperative interaction between different kinds of nonlinear photocurrents would be a complex yet interesting issue. Herein, we have prepared tellurium (Te) nanotube films to study the transient nonlinear photocurrent utilizing terahertz (THz) emission spectroscopy excited by a femtosecond pulse laser. The THz wave is generated from the interplay between the ultrafast shift current and ultrafast photon drag current, which are ascribed to the photogalvanic effect (PGE) and photon drag effect (PDE), respectively. According to the THz emission spectroscopy excited from opposite incident planes, the contribution ratio of the PDE and PGE is calculated as 1.2:1 for the THz parallel E THz-p component and 1:1 for the perpendicular E THz-s component under the p-polarized excitation. The different ratios between these two components are related to the different nonlinear susceptibility tensor elements. In particular, the contribution of the PDE and PGE can be dynamically modulated by the polarization angle of the incident laser, which further flexibly modulates both E THz-p and E THz-s . As such, the reconstructed THz wave is elliptically polarized with the fixed ellipticity, while the major axis of the ellipse rotates clockwise with different magnitudes. These results highlight the THz emission spectroscopy as an effective tool to clarify the interplay mechanism between different nonlinear photocurrents, which could open a new avenue for ultrafast photovoltaic applications.

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Section: Introductionmentioning

confidence: 99%

Interplay between Ultrafast Shift Current and Ultrafast Photon Drag Current in Tellurium Nanotubes

Cao

Huang

et al. 2022

ACS Photonics

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“…The research on the interaction of atoms and molecules with intense laser pulses plays a key role in a comprehensive understanding of the nonlinear physics. Plenty of ultrafast processes are directly related to photoionization, which is the foundation of many strong field phenomena such as high harmonic generation (HHG), attosecond pulse synthetization [1][2][3][4][5], above threshold ionization (ATI) [6], and non-sequential double ionization (NSDI) [7]. NSDI has drawn much attention because of containing extensive information about collision dynamics and electron-electron correlation [8].…”

Section: Introductionmentioning

confidence: 99%

Controlling electron recollision with combined linear and circular polarization

Ben

Han²,

Yang³

et al. 2022

Front. Phys.

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We theoretically investigate the non-sequential double ionization of Ar atoms in the combined fields of linearly polarized laser and circularly polarized laser through 3D semiclassical simulations. By partially overlapping the two time-delayed multicycle laser pulses, we construct an optical waveform whose polarization ellipticity increase slowly for consecutive optical cycles. This composite laser pulses with the time-dependent ellipticity can tunnel-ionize atoms and steer the first tunneling electron to recollision with the second bound electron through different trajectories, in which the recollision occurs with different return times of the first ionized electron. Through tuning delay time between the two laser pulses, the double ionization yields and recollision trajectories with different return times can be controlled. The time-dependent ellipticity with different delay time can enhance or suppress the probability of different return times. This work provides a scheme exploring electron dynamics in few optical cycle or even subcycle time scale in a multicycle laser field without having to be limited to near-single-cycle laser pulses.

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“…Figure 4 shows the harmonic spots in the first order diffraction with the image quality optimized for the 35 th harmonic order (propagating through the optical axis of the focusing toroidal mirror at this particular azimuth angle of the grating). Although the focusing conditions for different harmonics can be different due to the inherent wavelength dependence of HHG [54][55][56][57], the measured diameters for a given harmonic were found to be similar after each monochromator stage and larger than the diffraction-limited size indicating that they are limited by the finite spot size of the XUV source (imaged in a one-to-one ratio throughout the beamline), which is estimated to be around 90 µm.…”

Section: Focusabilitymentioning

confidence: 97%

Spectrally tunable ultrashort monochromatized extreme ultraviolet pulses at 100 kHz

Csizmadia¹,

Filus²,

Grósz³

et al. 2022

Preprint

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We present the experimental realization of spectrally tunable, ultrashort, quasimonochromatic extreme ultraviolet (XUV) pulses generated at 100 kHz repetition rate in a user-oriented gas high harmonic generation (GHHG) beamline of the Extreme Light Infrastructure -Attosecond Light Pulse Source (ELI ALPS) facility. Versatile spectral and temporal shaping of the XUV pulses are accomplished with a double-grating, time-delay compensated monochromator accommodating the two composing stages in a novel, asymmetrical geometry. This configuration supports the achievement of high monochromatic XUV flux (2.8±0.9 × 10 10 photons/s) combined with ultrashort pulse duration (4.0±0.2 fs using 12.1±0.6 fs driving pulses) and small spot size (sub-100 µm). Focusability, spectral bandwidth, and overall photon flux of the produced radiation were investigated covering a wide range of instrumental configurations. Moreover, complete temporal (intensity and phase) characterization of the few-femtosecond monochromatic XUV pulses -a goal that is difficult to achieve by conventional reconstruction techniques -has been realized using ptychographic algorithm on experimentally recorded XUV-IR pump-probe traces. The presented results contribute to in-situ, time-resolved experiments accessing direct information on the electronic structure dynamics of novel target materials.

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Focusing Properties of High-Order Harmonics

Cited by 32 publications

References 52 publications

Interplay between Ultrafast Shift Current and Ultrafast Photon Drag Current in Tellurium Nanotubes

Interplay between Ultrafast Shift Current and Ultrafast Photon Drag Current in Tellurium Nanotubes

Controlling electron recollision with combined linear and circular polarization

Spectrally tunable ultrashort monochromatized extreme ultraviolet pulses at 100 kHz

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